Substance dependence
Overview
The section about substance dependence in the Diagnostic and Statistical Manual of Mental Disorders
Diagnostic and Statistical Manual of Mental Disorders
The Diagnostic and Statistical Manual of Mental Disorders is published by the American Psychiatric Association and provides a common language and standard criteria for the classification of mental disorders...

 (more specifically, the 2000 "text revision", the DSM-IV-TR) does not use the word addiction at all. It explains:
When an individual persists in use of alcohol or other drugs despite problems related to use of the substance, substance dependence may be diagnosed. Compulsive and repetitive use may result in tolerance to the effect of the drug and withdrawal symptoms when use is reduced or stopped.
Encyclopedia
The section about substance dependence in the Diagnostic and Statistical Manual of Mental Disorders
Diagnostic and Statistical Manual of Mental Disorders
The Diagnostic and Statistical Manual of Mental Disorders is published by the American Psychiatric Association and provides a common language and standard criteria for the classification of mental disorders...

 (more specifically, the 2000 "text revision", the DSM-IV-TR) does not use the word addiction at all. It explains:
When an individual persists in use of alcohol or other drugs despite problems related to use of the substance, substance dependence may be diagnosed. Compulsive and repetitive use may result in tolerance to the effect of the drug and withdrawal symptoms when use is reduced or stopped. This, along with Substance abuse
Substance abuse
A substance-related disorder is an umbrella term used to describe several different conditions associated with several different substances .A substance related disorder is a condition in which an individual uses or abuses a...

 are considered Substance Use Disorders....

This is far from the only way of defining the relevant terms, however (see "Defining terms" section below).

Brief overview

Doug Sellman at the National Addiction Center offers what he calls "The 10 most important things to know about addiction". He offers the following points, before explaining them in more detail (although even his full paper does not presume to be able to discuss all the important facts about addiction). First, Sellman says that the most important thing to know about addiction may be that addiction is "fundamentally about compulsive behaviour" (see also Obsessive compulsive disorder)". Second of all, such habits originate outside of consciousness
Consciousness
Consciousness is a term that refers to the relationship between the mind and the world with which it interacts. It has been defined as: subjectivity, awareness, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind...

 (i.e. from the unconscious mind
Unconscious mind
The unconscious mind is a term coined by the 18th century German romantic philosopher Friedrich Schelling and later introduced into English by the poet and essayist Samuel Taylor Coleridge...

). The compulsive sequence of behaviours are so practiced that they can be extremely difficult to avoid initiating, and even harder to interrupt. Sellman maintains, thirdly, that addiction is 50% heritable. In other words, family background and genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

 play a large role (see also Nature versus Nurture
Nature versus nurture
The nature versus nurture debate concerns the relative importance of an individual's innate qualities versus personal experiences The nature versus nurture debate concerns the relative importance of an individual's innate qualities ("nature," i.e. nativism, or innatism) versus personal experiences...

).

The fourth most important thing is that people with addictions often have other psychiatric problems (e.g. psychiatric disorders), which can complicate matters. Next, fifth, Sellman explains that addiction is characterized by frequent relapse
Relapse
Relapse, in relation to drug misuse, is resuming the use of a drug or a dependent substance after one or more periods of abstinence. The term is a landmark feature of both substance dependence and substance abuse, which are learned behaviors, and is maintained by neuronal adaptations that mediate...

, and that one should not expect to overcome addiction on the first try. The sixth point he makes is that the different forms of psychotherapy
Psychotherapy
Psychotherapy is a general term referring to any form of therapeutic interaction or treatment contracted between a trained professional and a client or patient; family, couple or group...

 all produce similar results that may be based on what is common between them (i.e. a strong bond with a trusted friend). Sellman's seventh most important thing about addiction is that ‘come back when you're motivated’ is an inappropriate approach to addiction. Individuals have very specific problems, and so it is important to find ways to engage the addicted individual (Sellman describes how empathy
Empathy
Empathy is the capacity to recognize and, to some extent, share feelings that are being experienced by another sapient or semi-sapient being. Someone may need to have a certain amount of empathy before they are able to feel compassion. The English word was coined in 1909 by E.B...

 is crucial, for example). His next, eighth point expands on this idea: Sellman says that doctors should apply as broad an approach to the individual as possible. This means combining various rejuvenating approaches, including prescription drugs, family therapy, social and legal support, providing accommodations, and more. The ninth important thing about addiction is that epiphanies
Epiphany (feeling)
An epiphany is the sudden realization or comprehension of the essence or meaning of something...

 are rare - even though they are the most popular kind of story to spread.

The tenth, and final important thing that Sellman explains is that change takes time (months or years of failing and trying more). He advocates for the importance of patience and persistence in practicing new behaviours over long periods of time. He concludes by appealing to all professionals involved in combating addiction; he asks that they all work together - because the combined knowledge of all fields is what is required.

Defining terms

According to the current Diagnostic and Statistical Manual of Mental Disorders
Diagnostic and Statistical Manual of Mental Disorders
The Diagnostic and Statistical Manual of Mental Disorders is published by the American Psychiatric Association and provides a common language and standard criteria for the classification of mental disorders...

 (DSM-IV), substance dependence is defined as:
When an individual persists in use of alcohol or other drugs despite problems related to use of the substance, substance dependence may be diagnosed. Compulsive and repetitive use may result in tolerance to the effect of the drug and withdrawal symptoms when use is reduced or stopped. This, along with Substance Abuse
Substance abuse
A substance-related disorder is an umbrella term used to describe several different conditions associated with several different substances .A substance related disorder is a condition in which an individual uses or abuses a...

 are considered Substance Use Disorders....

Substance dependence can be diagnosed with physiological dependence
Physical dependence
Physical dependence refers to a state resulting from chronic use of a drug that has produced tolerance and where negative physical symptoms of withdrawal result from abrupt discontinuation or dosage reduction...

, evidence of tolerance or withdrawal, or without physiological dependence.

By the American Society of Addiction Medicine
American Society of Addiction Medicine
The American Society of Addiction Medicine is a physician society with a focus on addiction and its treatment.- History :ASAM has its roots in research and clinical traditions that pre-date its founding in the early 1950s, when Ruth Fox, M.D. began regular meetings with other physicians interested...

 definition, drug addiction differs from drug dependence and drug tolerance. It is, both among scientists and other writers, quite usual to allow the concept of drug addiction to include persons who are not drug abusers according to the definition of the American Society of Addiction Medicine. The term drug addiction is then used as a category which may include the same persons who, under the DSM-IV, can be given the diagnosis of substance dependence or substance abuse
Substance abuse
A substance-related disorder is an umbrella term used to describe several different conditions associated with several different substances .A substance related disorder is a condition in which an individual uses or abuses a...

. (See also DSM-IV Codes
DSM-IV Codes
Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision, also known as DSM-IV-TR, is a manual published by the American Psychiatric Association that includes all currently recognized mental health disorders...

)

The terms abuse and addiction have been defined and re-defined over the years. The 1957 World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

 (WHO) Expert Committee on Addiction-Producing Drugs defined addiction and habituation as components of drug abuse
Drug abuse
Substance abuse, also known as drug abuse, refers to a maladaptive pattern of use of a substance that is not considered dependent. The term "drug abuse" does not exclude dependency, but is otherwise used in a similar manner in nonmedical contexts...

:
Drug addiction is a state of periodic or chronic intoxication produced by the repeated consumption of a drug (natural or synthetic). Its characteristics include: (i) an overpowering desire or need (compulsion) to continue taking the drug and to obtain it by any means; (ii) a tendency to increase the dose; (iii) a psychic (psychological) and generally a physical dependence
Physical dependence
Physical dependence refers to a state resulting from chronic use of a drug that has produced tolerance and where negative physical symptoms of withdrawal result from abrupt discontinuation or dosage reduction...

 on the effects of the drug; and (iv) detrimental effects on the individual and on society.


Drug habituation (habit) is a condition resulting from the repeated consumption of a drug. Its characteristics include (i) a desire (but not a compulsion) to continue taking the drug for the sense of improved well-being which it engenders; (ii) little or no tendency to increase the dose; (iii) some degree of psychic dependence on the effect of the drug, but absence of physical dependence and hence of an abstinence syndrome [withdrawal], and (iv) detrimental effects, if any, primarily on the individual.


In 1964, a new WHO committee found these definitions to be inadequate, and suggested using the blanket term "drug dependence":
The definition of addiction gained some acceptance, but confusion in the use of the terms addiction and habituation and misuse of the former continued. Further, the list of drugs abused increased in number and diversity. These difficulties have become increasingly apparent and various attempts have been made to find a term that could be applied to drug abuse generally. The component in common appears to be dependence, whether psychic or physical or both. Hence, use of the term "drug dependence", with a modifying phase linking it to a particular drug type in order to differentiate one class of drugs from another, had been given most careful consideration. The Expert Committee recommends substitution of the term "drug dependence" for the terms "drug addiction" and "drug habituation".


The committee did not clearly define dependence, but did go on to clarify that there was a distinction between physical and psychological ("psychic") dependence. It said that drug abuse was "a state of psychic dependence or physical dependence, or both, on a drug, arising in a person following administration of that drug on a periodic or continued basis." Psychic dependence was defined as a state in which "there is a feeling of satisfaction and psychic drive that requires periodic or continuous administration of the drug to produce pleasure or to avoid discomfort" and all drugs were said to be capable of producing this state:
There is scarcely any agent which can be taken into the body to which some individuals will not get a reaction satisfactory or pleasurable to them, persuading them to continue its use even to the point of abuse – that is, to excessive or persistent use beyond medical need.


The 1957 and 1964 definitions of addiction, dependence and abuse persist to the present day in medical literature. It should be noted that at this time (2006) the Diagnostic Statistical Manual (DSM-IV-TR) now spells out specific criteria for defining abuse and dependence. (DSM-IV-TR) uses the term substance dependence instead of addiction; a maladaptive pattern of substance abuse, leading to clinically significant impairment or distress, as manifested by three (or more) specified criteria, occurring at any time in the same 12-month period. This definition is also applicable on drugs with smaller or nonexistent physical signs of withdrawal, e.g., cannabis.

In 2001, the American Academy of Pain Medicine, the American Pain Society, and the American Society of Addiction Medicine jointly issued "Definitions Related to the Use of Opioids for the Treatment of Pain", which defined the following terms:

Addiction is a primary, chronic, neurobiologic disease, with genetic, psychosocial, and environmental factors influencing its development and manifestations. It is characterized by behaviors that include one or more of the following: impaired control over drug use, compulsive use, continued use despite harm, and craving.


Physical dependence
Physical dependence
Physical dependence refers to a state resulting from chronic use of a drug that has produced tolerance and where negative physical symptoms of withdrawal result from abrupt discontinuation or dosage reduction...

 is a state of being that is manifested by a drug class specific withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood level of the drug, and/or administration of an antagonist.


Tolerance is the body's physical adaptation to a drug: greater amounts of the drug are required over time to achieve the initial effect as the body "gets used to" and adapts to the intake.


Pseudo addiction is a term which has been used to describe patient behaviors that may occur when pain is undertreated. Patients with unrelieved pain may become focused on obtaining medications, may "clock watch," and may otherwise seem inappropriately "drug seeking." Even such behaviors as illicit drug use and deception can occur in the patient's efforts to obtain relief. Pseudoaddiction can be distinguished from true addiction in that the behaviors resolve when pain is effectively treated.


A definition of addiction proposed by professor Nils Bejerot
Nils Bejerot
Nils Bejerot was a Swedish psychiatrist and criminologist best known for his work on drug abuse and for coining the phrase, Stockholm syndrome.-Work:...

:
An emotional fixation (sentiment) acquired through learning, which intermittently or continually expresses itself in purposeful, stereotyped behavior with the character and force of a natural drive, aiming at a specific pleasure or the avoidance of a specific discomfort.

Causes

Drugs known to cause addiction include both legal and illegal drugs as well as prescription
Prescription drug
A prescription medication is a licensed medicine that is regulated by legislation to require a medical prescription before it can be obtained. The term is used to distinguish it from over-the-counter drugs which can be obtained without a prescription...

 or over-the-counter drug
Over-the-counter drug
Over-the-counter drugs are medicines that may be sold directly to a consumer without a prescription from a healthcare professional, as compared to prescription drugs, which may be sold only to consumers possessing a valid prescription...

s, according to the definition of the American Society of Addiction Medicine.
  • Stimulant
    Stimulant
    Stimulants are psychoactive drugs which induce temporary improvements in either mental or physical function or both. Examples of these kinds of effects may include enhanced alertness, wakefulness, and locomotion, among others...

    s (psychic addiction, moderate to severe; withdrawal is purely psychological and psychosomatic):
    • Amphetamine
      Amphetamine
      Amphetamine or amfetamine is a psychostimulant drug of the phenethylamine class which produces increased wakefulness and focus in association with decreased fatigue and appetite.Brand names of medications that contain, or metabolize into, amphetamine include Adderall, Dexedrine, Dextrostat,...

       and methamphetamine
      Methamphetamine
      Methamphetamine is a psychostimulant of the phenethylamine and amphetamine class of psychoactive drugs...

    • Cocaine
      Cocaine
      Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system, an appetite suppressant, and a topical anesthetic...

    • Caffeine
      Caffeine
      Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...

  • Sedative
    Sedative
    A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....

    s and hypnotic
    Hypnotic
    Hypnotic drugs are a class of psychoactives whose primary function is to induce sleep and to be used in the treatment of insomnia and in surgical anesthesia...

    s (psychic addiction, mild to severe, and physiological addiction, severe; abrupt withdrawal may be fatal):
    • Alcohol
      Alcohol
      In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

    • Barbiturate
      Barbiturate
      Barbiturates are drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia. They are also effective as anxiolytics, as hypnotics, and as anticonvulsants...

      s
    • Benzodiazepines, particularly flunitrazepam
      Flunitrazepam
      Flunitrazepam is marketed as a potent hypnotic, sedative, anticonvulsant, anxiolytic, amnestic, and skeletal muscle relaxant drug most commonly known as Rohypnol...

      , triazolam
      Triazolam
      Triazolam is a benzodiazepine drug. It possesses pharmacological properties similar to that of other benzodiazepines, but it is generally only used as a sedative to treat severe insomnia...

      , temazepam
      Temazepam
      Temazepam is an intermediate-acting 3-hydroxy benzodiazepine. It is mostly prescribed for the short-term treatment of sleeplessness in patients who have difficulty maintaining sleep...

      , and nimetazepam
      Nimetazepam
      Nimetazepam is an intermediate-acting hypnotic drug which is a benzodiazepine derivative. It was first synthesized by a team at Hoffmann-La Roche in 1962. It possesses hypnotic, anxiolytic, sedative, and skeletal muscle relaxant properties. Nimetazepam is also an anticonvulsant. It is sold in 5 mg...

       Z- drugs like Zimovane have a similar effect in the body to Benzodiazepines.
    • Methaqualone
      Methaqualone
      Methaqualone is a sedative-hypnotic drug that is similar in effect to barbiturates, a general central nervous system depressant. The sedative-hypnotic activity was first noted by Indian researchers in the 1950s and in 1962 methaqualone itself was patented in the US by Wallace and Tiernan...

       and the related quinazolinone
      Quinazolinone
      Quinazolinone is a heterocyclic chemical compound. There are two structural isomers, 2-quinazolinone and 4-quinazolinone, with the 4-isomer being the more common.-Derivatives:...

       sedative-hypnotics
  • Opiate
    Opiate
    In medicine, the term opiate describes any of the narcotic opioid alkaloids found as natural products in the opium poppy plant.-Overview:Opiates are so named because they are constituents or derivatives of constituents found in opium, which is processed from the latex sap of the opium poppy,...

     and opioid
    Opioid
    An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...

     analgesics (psychic addiction, mild to severe, physiological addiction, mild to severe; abrupt withdrawal is unlikely to be fatal):
    • Morphine
      Morphine
      Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...

       and codeine
      Codeine
      Codeine or 3-methylmorphine is an opiate used for its analgesic, antitussive, and antidiarrheal properties...

      , the two naturally occurring opiate analgesics
    • Semi-synthetic opiates, such as heroin (diacetylmorphine; morphine diacetate), oxycodone
      Oxycodone
      Oxycodone is an opioid analgesic medication synthesized from opium-derived thebaine. It was developed in 1916 in Germany, as one of several new semi-synthetic opioids in an attempt to improve on the existing opioids: morphine, diacetylmorphine , and codeine.Oxycodone oral medications are generally...

      , buprenorphine
      Buprenorphine
      Buprenorphine is a semi-synthetic opioid that is used...

      , and hydromorphone
      Hydromorphone
      Hydromorphone, a more common synonym for dihydromorphinone, commonly a hydrochloride is a very potent centrally-acting analgesic drug of the opioid class. It is a derivative of morphine, to be specific, a hydrogenated ketone thereof and, therefore, a semi-synthetic drug...

    • Fully synthetic opioids, such as fentanyl, meperidine/pethidine, and methadone
      Methadone
      Methadone is a synthetic opioid, used medically as an analgesic and a maintenance anti-addictive for use in patients with opioid dependency. It was developed in Germany in 1937...

  • Nicotine
    Nicotine
    Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...


Addictive drugs also include a large number of substrates that are currently considered to have no medical value and are not available over the counter or by prescription.

Several theories of drug addiction exist, some of the main ones being genetic predisposition, the self-medication theory, and factors involved with social/economic development. It has long been established that genetic factors along with social and psychological factors are contributors to addiction. A common theory along these lines is the self-medication hypotheses. Epidemiological studies estimate that genetic factors account for 40-60% of the risk factors for alcoholism. Similar rates of heritability for other types of drug addiction have been indicated by other studies (Kendler, 1994). Knestler hypothesized in 1964 that a gene or group of genes might contribute to predisposition to addiction in several ways. For example, altered levels of a normal protein due to environmental factors could then change the structure or functioning of specific brain circuits during development. These altered brain circuits could change the susceptibility of an individual to an initial drug use experience. In support of this hypothesis, animal studies have shown that environmental factors such as stress can affect an animal's genotype.

Addictive potential

The addictive potential of a drug varies from substance to substance, and from individual to individual. Dose, frequency, pharmacokinetics of a particular substance, route of administration, and time are critical factors for developing a drug addiction.

An article in The Lancet
The Lancet
The Lancet is a weekly peer-reviewed general medical journal. It is one of the world's best known, oldest, and most respected general medical journals...

compared the harm and addiction of 20 drugs, using a scale from 0 to 3 for physical addiction, psychological addiction, and pleasure to create a mean score for addiction. A caffeine
Caffeine
Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...

 control was not included in the study. Selected results can be seen in the chart below.
Drug Mean Pleasure Psychological Dependence Physical Dependence
Heroin  3.00 3.0 3.0 3.0
Cocaine
Cocaine
Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system, an appetite suppressant, and a topical anesthetic...

 
2.37 3.0 2.8 1.3
Alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

 
1.93 2.3 1.9 1.6
Tobacco
Tobacco
Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...

 
2.23 2.3 2.6 1.8
Barbiturates  2.01 2.0 2.2 1.8
Benzodiazepines  1.83 1.7 2.1 1.8
Methamphetamine
Methamphetamine
Methamphetamine is a psychostimulant of the phenethylamine and amphetamine class of psychoactive drugs...

 
1.67 2.0 1.9 1.1
LSD
LSD
Lysergic acid diethylamide, abbreviated LSD or LSD-25, also known as lysergide and colloquially as acid, is a semisynthetic psychedelic drug of the ergoline family, well known for its psychological effects which can include altered thinking processes, closed and open eye visuals, synaesthesia, an...

 
1.23 2.2 1.1 0.3
Ecstasy  1.13 1.5 1.2 0.7

Self-medication hypotheses

Espoused by both psychoanalysts and biological researchers, self-medication hypotheses predict that certain individuals abuse drugs in an attempt to self-medicate their unique and seemingly intolerable states of mind. The self-medication theory has a long history. Freud in 1884, first raised this concept in noting the anti-depressing properties of cocaine. Stress has long been recognized as a major contributor for drug cravings and relapse and is therefore supportive of the self-medication theory. In line with this theory, a person's use of a particular drug of choice is not an accident, but rather it is chosen for its pharmacological effect in relieving stressful symptoms or unwanted feelings. Research has shown that people who survive disasters are prone to stress-related disorders such as posttraumatic stress disorder (PTSD) and depression. People who experience major trauma in their life experiences may self-medicate with alcohol or other drugs to relieve the symptoms of PTSD and depression.

Social development

Social development and adjustment factors also play a role in drug abuse and addiction. An assumption of the developmental perspective, as mentioned by Thornberry 1987, is that the course of one's life is a process in which life circumstances change, milestones are met or missed and new social roles are created while old ones are abandoned. There are well known and widely accepted norms about when certain developmental events should happen in a person's life. Studies of the social factors involved in drug use have mostly focused either on adolescence or young adulthood, but surprisingly a significant amount of cocaine users may not initiate use until middle adulthood. The majority of people enter into adult social roles on schedule. However, some people enter these roles earlier or later than their same-age peers. The developmental perspective predicts that this will lead to less than satisfactory adjustment and possibly negative consequences including drug and alcohol dependence

Pathophysiology

Researchers have conducted numerous investigations using animal models and functional brain imaging on humans in order to define the mechanisms underlying drug addiction in the brain. This intriguing topic incorporates several areas of the brain and synaptic changes, or neuroplasticity
Neuroplasticity
Neuroplasticity is a non-specific neuroscience term referring to the ability of the brain and nervous system in all species to change structurally and functionally as a result of input from the environment. Plasticity occurs on a variety of levels, ranging from cellular changes involved in...

, which occurs in these areas.

Acute effects

Acute (or recreational
Recreational drug use
Recreational drug use is the use of a drug, usually psychoactive, with the intention of creating or enhancing recreational experience. Such use is controversial, however, often being considered to be also drug abuse, and it is often illegal...

) use of most psychoactive drugs causes the release and prolonged action of dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...

 and serotonin
Serotonin
Serotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...

 within the reward circuit. Different types of drugs produce these effects by different methods. Dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...

 (DA) appears to harbor the largest effect and its action is characterized. DA binds to the D1 receptor, triggering a signaling cascade within the cell. cAMP-dependent protein kinase
CAMP-dependent protein kinase
In cell biology, Protein kinase A refers to a family of enzymes whose activity is dependent on cellular levels of cyclic AMP . PKA is also known as cAMP-dependent protein kinase...

 (PKA) phosphorylates cAMP response element binding protein (CREB), a transcription factor, which induces the transcription of certain genes including C-Fos
C-Fos
In the field of molecular biology and Genetics, c-Fos is a protein encoded by the FOS gene.-Structure and function:c-Fos is a cellular proto-oncogene belonging to the immediate early gene family of transcription factors. c-Fos has a leucine-zipper DNA binding domain, and a transactivation domain at...

.

Reward circuit

When examining the biological basis of drug addiction, one must first understand the pathways in which drugs act and how drugs can alter those pathways. The reward circuit
Reward system
In neuroscience, the reward system is a collection of brain structures which attempts to regulate and control behavior by inducing pleasurable effects...

, also referred to as the mesolimbic system, is characterized by the interaction of several areas of the brain.
  • The ventral tegmental area
    Ventral tegmentum
    The ventral tegmentum , better known as the ventral tegmental area , is a group of neurons located close to the midline on the floor of the midbrain...

     (VTA) consists of dopaminergic
    Dopaminergic
    Dopaminergic means related to the neurotransmitter dopamine. For example, certain proteins such as the dopamine transporter , vesicular monoamine transporter 2 , and dopamine receptors can be classified as dopaminergic, and neurons which synthesize or contain dopamine and synapses with dopamine...

     neurons which respond to glutamate. These cells respond when stimuli indicative of a reward are present. The VTA supports learning and sensitization development and releases dopamine
    Dopamine
    Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...

     (DA) into the forebrain. These neurons also project and release DA into the nucleus accumbens, through the mesolimbic pathway
    Mesolimbic pathway
    The mesolimbic pathway is one of the dopaminergic pathways in the brain. The pathway begins in the ventral tegmental area of the midbrain and connects to the limbic system via the nucleus accumbens, the amygdala, and the hippocampus as well as to the medial prefrontal cortex...

    . Virtually all drugs causing drug addiction increase the dopamine release in the mesolimbic pathway, in addition to their specific effects.
  • The nucleus accumbens
    Nucleus accumbens
    The nucleus accumbens , also known as the accumbens nucleus or as the nucleus accumbens septi , is a collection of neurons and forms the main part of the ventral striatum...

     (NAc) consists mainly of medium-spiny projection neurons (MSNs), which are GABA
    Gabâ
    Gabâ or gabaa, for the people in many parts of the Philippines), is the concept of a non-human and non-divine, imminent retribution. A sort of negative karma, it is generally seen as an evil effect on a person because of their wrongdoings or transgressions...

     neurons. The NAcc is associated with acquiring and eliciting conditioned behaviors and involved in the increased sensitivity to drugs as addiction progresses.
  • The prefrontal cortex
    Prefrontal cortex
    The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...

    , more specifically the anterior cingulate and orbitofrontal
    Orbitofrontal cortex
    The orbitofrontal cortex is a prefrontal cortex region in the frontal lobes in the brain which is involved in the cognitive processing of decision-making...

     cortices, is important for the integration of information which contributes to whether a behavior will be elicited. It appears to be the area in which motivation originates and the salience of stimuli are determined.
  • The basolateral amygdala
    Basolateral Amygdala
    The Basolateral Amygdala is a major limbic-related region within the brain.The basolateral amygdala projects heavily to the nucleus accumbens. The nucleus accumbens is regarded as the limbic-motor interface, in view of these limbic afferent and its somatomotor and autonomic efferent connections...

     projects into the NAcc and is thought to be important for motivation as well.
  • More evidence is pointing towards the role of the hippocampus
    Hippocampus
    The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

     in drug addiction because of its importance in learning and memory. Much of this evidence stems from investigations manipulating cells in the hippocampus alters dopamine levels in NAcc and firing rates of VTA dopaminergic cells.

Role of dopamine

Nearly all addictive drugs, directly or indirectly, act upon the brain’s reward system by flooding the circuit with dopamine. As a person continues to overstimulate the “reward circuit”, the brain adapts to the overwhelming surges in dopamine by producing less of the hormones or by reducing the number of receptors in the reward circuit. As a result, the chemical’s impact on the reward circuit is lessened, reducing the drug-abuser’s ability to enjoy the things that previously brought pleasure. This decrease compels those addicted to the dopaminergenic-effect of the drug, to increase the drug consumption in order to re-create the earlier or initial experiences and to bring their "feel-good" hormone level back to normal —an effect known as tolerance. Development of dopamine tolerance can eventually lead to profound changes in neurons and brain circuits, with the potential to severely compromise the long-term health and functioning of a person's brain. Modern antipsychotics are designed to block dopamine function. Unfortunately, this blocking can also cause relapses into depression, and increases in addictive behaviors.

Stress response

In addition to the reward circuit, it is hypothesized that stress mechanisms also play a role in addiction. Koob and Kreek have hypothesized that during drug use, the corticotropin-releasing factor
Corticotropin-releasing hormone
Corticotropin-releasing hormone , originally named corticotropin-releasing factor , and also called corticoliberin, is a polypeptide hormone and neurotransmitter involved in the stress response...

 (CRF) activates the hypothalamic-pituitary-adrenal axis
Hypothalamic-pituitary-adrenal axis
The hypothalamic-pituitary-adrenal axis , also known as thelimbic-hypothalamic-pituitary-adrenal axis and, occasionally, as the hypothalamic-pituitary-adrenal-gonadotropic axis, is a complex set of direct influences and feedback interactions among the hypothalamus, the pituitary gland ,...

 (HPA) and other stress systems in the extended amygdala
Amygdala
The ' are almond-shaped groups of nuclei located deep within the medial temporal lobes of the brain in complex vertebrates, including humans. Shown in research to perform a primary role in the processing and memory of emotional reactions, the amygdalae are considered part of the limbic system.-...

. This activation influences the dysregulated emotional state associated with drug addiction. They have found that as drug use escalates, so does the presence of CRF in human cerebrospinal fluid
Cerebrospinal fluid
Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...

 (CSF). In rat models, the separate use of CRF antagonists and CRF receptor antagonists both decreased self-administration of the drug of study. Other studies in this review showed a dysregulation in other hormones associated with the HPA axis, including enkephalin
Enkephalin
An enkephalin is a pentapeptide involved in regulating nociception in the body. The enkephalins are termed endogenous ligands, or specifically endorphins, as they are internally derived and bind to the body's opioid receptors. Discovered in 1975, two forms of enkephalin were revealed, one...

 which is an endogenous opioid peptide
Opioid peptide
Opioid peptides are short sequences of amino acids that bind to opioid receptors in the brain; opiates and opioids mimic the effect of these peptides. Opioid peptides may be produced by the body itself, for example endorphins. The effects of these peptides vary, but they all resemble opiates...

 that regulates pain. It also appears that the µ-opioid receptor
Mu Opioid receptor
The μ-opioid receptors are a class of opioid receptors with high affinity for enkephalins and beta-endorphin but low affinity for dynorphins. They are also referred to as μ opioid peptide receptors. The prototypical μ receptor agonist is the opium alkaloid morphine; μ refers to morphine...

 system, which enkephalin acts on, is influential in the reward system and can regulate the expression of stress hormones.

Behavior

Understanding how learning
Learning
Learning is acquiring new or modifying existing knowledge, behaviors, skills, values, or preferences and may involve synthesizing different types of information. The ability to learn is possessed by humans, animals and some machines. Progress over time tends to follow learning curves.Human learning...

 and behavior
Behavior
Behavior or behaviour refers to the actions and mannerisms made by organisms, systems, or artificial entities in conjunction with its environment, which includes the other systems or organisms around as well as the physical environment...

 work in the reward circuit can help understand the action of addictive drugs. Drug addiction is characterized by strong, drug seeking behaviors in which the addict persistently craves and seeks out drugs, despite the knowledge of harmful consequences. Addictive drugs produce a reward, which is the euphoric feeling resulting from sustained dopamine concentrations in the synaptic cleft of neurons in the brain. Operant conditioning
Operant conditioning
Operant conditioning is a form of psychological learning during which an individual modifies the occurrence and form of its own behavior due to the association of the behavior with a stimulus...

 is exhibited in drug addicts as well as laboratory mice, rats, and primates; they are able to associate an action or behavior, in this case seeking out the drug, with a reward, which is the effect of the drug. Evidence shows that this behavior is most likely a result of the synaptic changes which have occurred due to repeated drug exposure. The drug seeking behavior is induced by glutamatergic projections from the prefrontal cortex to the NAc. This idea is supported with data from experiments showing the drug seeking behavior can be prevented following the inhibition of AMPA
AMPA
AMPA is a compound that is a specific agonist for the AMPA receptor, where it mimics the effects of the neurotransmitter glutamate....

 glutamate receptors and glutamate release in the NAc.

Allostasis

Allostasis
Allostasis
Allostasis is the process of achieving stability, or homeostasis, through physiological or behavioral change. This can be carried out by means of alteration in HPA axis hormones, the autonomic nervous system, cytokines, or a number of other systems, and is generally adaptive in the short term...

 is the process of achieving stability through changes in behavior as well as physiological features. As a person progresses into drug addiction, he or she appears to enter a new allostatic state, defined as divergence from normal levels of change which persist in a chronic state. Addiction to drugs can cause damage to a brain and body as an organism enters the pathological state; the cost stemming from damage is known as allostatic load. The dysregulation of allostasis gradually occurs as the reward from the drug decreases and the ability to overcome the depressed state following drug use begins to decrease as well. The resulting allostatic load creates a constant state of depression relative to normal allostatic changes. What pushes this decrease is the propensity of drug users to take the drug before the brain and body have returned to original allostatic levels, producing a constant state of stress. Therefore, the presence of environmental stressors may induce stronger drug seeking behaviors.

Neuroplasticity

Neuroplasticity
Neuroplasticity
Neuroplasticity is a non-specific neuroscience term referring to the ability of the brain and nervous system in all species to change structurally and functionally as a result of input from the environment. Plasticity occurs on a variety of levels, ranging from cellular changes involved in...

 is the putative mechanism behind learning and memory. It involves physical changes in the synapses between two communicating neurons, characterized by increased gene expression, altered cell signaling, and the formation of new synapses between the communicating neurons. When addictive drugs are present in the system, they appear to hijack this mechanism in the reward system so that motivation is geared towards procuring the drug rather than natural rewards. Depending on the history of drug use, excitatory synapses in the nucleus accumbens
Nucleus accumbens
The nucleus accumbens , also known as the accumbens nucleus or as the nucleus accumbens septi , is a collection of neurons and forms the main part of the ventral striatum...

(NAc) experience two types of neuroplasticity: long-term potentiation
Long-term potentiation
In neuroscience, long-term potentiation is a long-lasting enhancement in signal transmission between two neurons that results from stimulating them synchronously. It is one of several phenomena underlying synaptic plasticity, the ability of chemical synapses to change their strength...

 (LTP) and long-term depression
Long-term depression
Long-term depression , in neurophysiology, is an activity-dependent reduction in the efficacy of neuronal synapses lasting hours or longer. LTD occurs in many areas of the CNS with varying mechanisms depending upon brain region and developmental progress...

 (LTD). Using mice as a model, Kourrich et al. showed that chronic exposure to cocaine increases the strength of synapses in NAc after a 10-14 day withdrawal period, while strengthened Synapses did not appear within a 24 hour withdrawal period after repeated cocaine exposure. A single dose of cocaine did not elicit any attributes of a strengthened synapse. When drug-experienced mice were challenged with one dose of cocaine, synaptic depression occurred. Therefore, it seems the history of cocaine exposure along with withdrawal times affects the direction of glutamatergic plasticity in the NAc.

Once a person has transitioned from drug use to addiction, behavior becomes completely geared towards seeking the drug, even though addicts report the euphoria is not as intense as it once was. Despite the differing actions of drugs during acute use, the final pathway of addiction is the same. Another aspect of drug addiction is a decreased response to normal biological stimuli, such as food, sex, and social interaction. Through functional brain imaging of patients addicted to cocaine, scientists have been able to visualize increased metabolic activity in the anterior cingulate and orbitofrontal cortex
Orbitofrontal cortex
The orbitofrontal cortex is a prefrontal cortex region in the frontal lobes in the brain which is involved in the cognitive processing of decision-making...

 (areas of the prefrontal cortex) in the brain of these subjects. The hyperactivity of these areas of the brain in addicted subjects is involved in the more intense motivation to find the drug rather than seeking natural rewards, as well as an addict's decreased ability to overcome this urge. Brain imaging has also shown cocaine-addicted subjects to have decreased activity, as compared to non-addicts, in their prefrontal cortex when presented with stimuli associated with natural rewards. The transition from recreational drug use to addiction occurs in gradual stages and is produced by the effect of the drug of choice on the neuroplasticity of the neurons found in the reward circuit. During events preceding addiction, cravings are produced by the release of dopamine (DA) in the prefrontal cortex. As a person transitions from drug use to addiction, the release of DA in the NAc becomes unnecessary to produce cravings; rather, DA transmission decreases while increased metabolic activity in the orbitofrontal cortex contributes to cravings. At this time a person may experience the signs of depression if cocaine is not used. Before a person becomes addicted and exhibits drug-seeking behavior, there is a time period in which the neuroplasticity is reversible. Addiction occurs when drug-seeking behavior is exhibited and the vulnerability to relapse persists, despite prolonged withdrawal; these behavioral attributes are the result of neuroplastic changes which are brought about by repeated exposure to drugs and are relatively permanent.

The exact mechanism behind a drug molecule's effect on synaptic plasticity is still unclear. However, neuroplasticity in glutamatergic projections seems to be a major result of repeated drug exposure. This type of synaptic plasticity results in LTP, which strengthens connections between two neurons; onset of this occurs quickly and the result is constant. In addition to glutamatergic neurons, dopaminergic neurons present in the VTA respond to glutamate and may be recruited earliest during neural adaptations caused by repeated drug exposure. As shown by Kourrich, et al., history of drug exposure and the time of withdrawal from last exposure appear to play an important role in the direction of plasticity in the neurons of the reward system.

An aspect of neuron development that may also play a part in drug-induced neuroplasticity is the presence of axon guidance molecules such as semaphorins and ephrins. After repeated cocaine treatment, altered expression (increase or decrease dependent on the type of molecule) of mRNA coding for axon guidance molecules occurred in rats. This may contribute to the alterations in the reward circuit characteristic of drug addiction.

Neurogenesis

Drug addiction also raises the issue of potential harmful effects on the development of new neurons in adults. Eisch and Harburg raise three new concepts they have extrapolated from the numerous recent studies on drug addiction. First, neurogenesis
Neurogenesis
Neurogenesis is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of...

 decreases as a result of repeated exposure to addictive drugs. A list of studies show that chronic use of opiate
Opiate
In medicine, the term opiate describes any of the narcotic opioid alkaloids found as natural products in the opium poppy plant.-Overview:Opiates are so named because they are constituents or derivatives of constituents found in opium, which is processed from the latex sap of the opium poppy,...

s, psychostimulants, nicotine, and alcohol decrease neurogenesis in mice and rats. Second, this apparent decrease in neurogenesis seems to be independent of HPA axis activation. Other environmental factors other than drug exposure such as age, stress and exercise, can also have an effect on neurogenesis by regulating the hypothalamic-pituitary-adrenal (HPA) axis. Mounting evidence suggests this for 3 reasons: small doses of opiates and psychostimulants increase corticosterone concentration in serum but with no effect of neurogenesis; although decreased neurogenesis is similar between self-administered and forced drug intake, activation of HPA axis is greater in self-administration subjects; and even after the inhibition of opiate induced increase of corticosterone, a decrease in neurogenesis occurred. These, of course, need to be investigated further. Last, addictive drugs appear to only affect proliferation in the subgranular zone
Neurogenesis
Neurogenesis is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of...

 (SGZ), rather than other areas associated with neurogenesis. The studies of drug use and neurogenesis may have implications on stem cell biology.

Psychological drug tolerance

The reward system is partly responsible for the psychological part of drug tolerance.

The CREB
CREB
CREB is a cellular transcription factor. It binds to certain DNA sequences called cAMP response elements , thereby increasing or decreasing the transcription of the downstream genes....

 protein, a transcription factor
Transcription factor
In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...

 activated by cyclic adenosine monophosphate
Cyclic adenosine monophosphate
Cyclic adenosine monophosphate is a second messenger important in many biological processes...

 (cAMP) immediately after a high, triggers gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

s that produce proteins such as dynorphin
Dynorphin
Dynorphins are a class of opioid peptides that arise from the precursor protein prodynorphin. When prodynorphin is cleaved during processing by proprotein convertase 2 , multiple active peptides are released: dynorphin A, dynorphin B, and α/β-neo-endorphin...

, which cuts off dopamine release and temporarily inhibits the reward circuit. In chronic drug users, a sustained activation of CREB thus forces a larger dose to be taken to reach the same effect. In addition it leaves the user feeling generally depressed and dissatisfied, and unable to find pleasure in previously enjoyable activities, often leading to a return to the drug for an additional "fix".

A similar mechanism, interfering also with the dopamine system, but relying on a different transcription factor, CEBPB
CEBPB
CCAAT/enhancer-binding protein beta is a protein that in humans is encoded by the CEBPB gene.- Function :The protein encoded by this intronless gene is a bZIP transcription factor that can bind as a homodimer to certain DNA regulatory regions. It can also form heterodimers with the related proteins...

, has also been proposed. In this case dopamine release onto the nucleus accumbens neurons would trigger the increased synthesis of substance P
Substance P
In the field of neuroscience, substance P is a neuropeptide: an undecapeptide that functions as a neurotransmitter and as a neuromodulator. It belongs to the tachykinin neuropeptide family. Substance P and its closely related neuropeptide neurokinin A are produced from a polyprotein precursor...

 which, in turn, would increase the dopamine synthesis in the VTA. The effect of this positive feedback is suggested to be dampened by repeated substance abuse.

Sensitization

Sensitization is the increase in sensitivity to a drug after prolonged use. The proteins delta FosB and regulator of G-protein Signaling 9-2 (RGS9
RGS9
Regulator of G-protein signalling 9, also known as RGS9, is a human gene, which codes for a protein involved in regulation of signal transduction inside cells...

-2) are thought to be involved:

A transcription factor, known as delta FosB, is thought to activate genes that, counter to the effects of CREB
CREB
CREB is a cellular transcription factor. It binds to certain DNA sequences called cAMP response elements , thereby increasing or decreasing the transcription of the downstream genes....

, actually increase the user's sensitivity to the effects of the substance. Delta FosB slowly builds up with each exposure to the drug and remains activated for weeks after the last exposure—long after the effects of CREB have faded. The hypersensitivity that it causes is thought to be responsible for the intense cravings associated with drug addiction, and is often extended to even the peripheral cues of drug use, such as related behaviors or the sight of drug paraphernalia. There is some evidence that delta FosB even causes structural changes within the nucleus accumbens
Nucleus accumbens
The nucleus accumbens , also known as the accumbens nucleus or as the nucleus accumbens septi , is a collection of neurons and forms the main part of the ventral striatum...

, which presumably helps to perpetuate the cravings, and may be responsible for the high incidence of relapses that occur in treated drug addicts.

Regulator of G-protein Signaling 9-2 (RGS9-2) has recently been the subject of several animal knockout studies. Animals lacking RGS9-2 appear to have increased sensitivity to dopamine receptor agonists such as cocaine and amphetamines; over-expression of RGS9-2 causes a lack of responsiveness to these same agonists. RGS9-2 is believed to catalyze inactivation of the G-protein coupled D2 receptor by enhancing the rate of GTP hydrolysis of the G alpha subunit which transmits signals into the interior of the cell.

Individual mechanisms of effect

The basic mechanisms by which different substances activate the reward system
Reward system
In neuroscience, the reward system is a collection of brain structures which attempts to regulate and control behavior by inducing pleasurable effects...

 are as described above, but vary slightly among drug classes.

Depressants
Depressant
Depressant
A depressant, or central depressant, is a drug or endogenous compound that depresses the function or activity of a specific part of the brain...

s such as alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

, barbiturate
Barbiturate
Barbiturates are drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia. They are also effective as anxiolytics, as hypnotics, and as anticonvulsants...

s, and benzodiazepine
Benzodiazepine
A benzodiazepine is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring...

s work by increasing the affinity of the GABA receptor for its ligand; GABA. Narcotic
Narcotic
The term narcotic originally referred medically to any psychoactive compound with any sleep-inducing properties. In the United States of America it has since become associated with opioids, commonly morphine and heroin and their derivatives, such as hydrocodone. The term is, today, imprecisely...

s such as morphine
Morphine
Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...

 and heroin work by mimicking endorphin
Endorphin
Endorphins are endogenous opioid peptides that function as neurotransmitters. They are produced by the pituitary gland and the hypothalamus in vertebrates during exercise, excitement, pain, consumption of spicy food, love and orgasm, and they resemble the opiates in their abilities to produce...

s—chemicals produced naturally by the body which have effects similar to dopamine—or by disabling the neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...

s that normally inhibit the release of dopamine in the reward system. These substances (sometimes called "downers") typically facilitate relaxation and pain relief.

Stimulants
Stimulant
Stimulant
Stimulants are psychoactive drugs which induce temporary improvements in either mental or physical function or both. Examples of these kinds of effects may include enhanced alertness, wakefulness, and locomotion, among others...

s such as amphetamine
Amphetamine
Amphetamine or amfetamine is a psychostimulant drug of the phenethylamine class which produces increased wakefulness and focus in association with decreased fatigue and appetite.Brand names of medications that contain, or metabolize into, amphetamine include Adderall, Dexedrine, Dextrostat,...

s, nicotine
Nicotine
Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...

, and cocaine
Cocaine
Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system, an appetite suppressant, and a topical anesthetic...

 increase dopamine signaling in the reward system either by directly stimulating its release, or by blocking its absorption (see "Reuptake
Reuptake
Reuptake, or re-uptake, is the reabsorption of a neurotransmitter by a neurotransmitter transporter of a pre-synaptic neuron after it has performed its function of transmitting a neural impulse....

"). These substances (sometimes called "uppers") typically cause heightened alertness and energy. They cause a pleasant feeling in the body and euphoria, known as a high. Once this high wears off, the user may feel depressed. This makes them want another dose of the drug, and can worsen the addiction.

Management

Addiction is a complex but treatable condition. It is characterized by compulsive drug craving, seeking, and use that persist even if the user is aware of severe adverse consequences. For some people, addiction becomes chronic, with relapses possible even after long periods of abstinence. As a chronic condition addiction may require continued treatments to increase the intervals between relapses and diminish their intensity. Most people with substance misuse issues recover and lead fulfilling lives however a small minority need additional support, usually in the form of drug counselling delivered in the community. For a very small percentage of very complex users this is insufficient and they require intensive inpatient or a series of long term treatments. The ultimate goal of addiction treatment is to enable an individual to manage their substance misuse for some this may mean abstinence. Immediate goals are often to reduce substance abuse, improve the patient's ability to function, and minimize the medical and social complications of substance abuse and their addiction this is called Harm Reduction. People in treatment for addiction may need to change behavior to adopt a more healthful lifestyle.

Treatments for addiction vary widely according to the types of drugs involved, amount of drugs used, duration of the drug addiction, medical complications and the social needs of the individual. Determining the best type of recovery program for an addicted person depends on a number of factors, including: personality, drug(s) of choice, concept of spirituality or religion, mental or physical illness, and local availability and affordability of programs.

Many different ideas circulate regarding what is considered a "successful" outcome in the recovery from addiction. Programs that emphasize controlled drinking exist for alcohol addiction. Opiate replacement therapy has been a medical standard of treatment for opioid addiction for many years.

Treatments and attitudes toward addiction vary widely among different countries. In the USA and developing countries, the goal of commissioners of treatment for drug dependence is generally total abstinence from all drugs. Other countries, particularly in Europe, argue the aims of treatment for drug dependence are more complex, with treatment aims including reduction in use to the point that drug use no longer interferes with normal activities such as work and family commitments; shifting the addict away from more dangerous routes of drug administration such as injecting to safer routes such as oral administration; reduction in crime committed by drug addicts; and treatment of other comorbid conditions such as AIDS
AIDS
Acquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...

, hepatitis
Hepatitis
Hepatitis is a medical condition defined by the inflammation of the liver and characterized by the presence of inflammatory cells in the tissue of the organ. The name is from the Greek hepar , the root being hepat- , meaning liver, and suffix -itis, meaning "inflammation"...

 and mental health disorders. These kinds of outcomes can be achieved without eliminating drug use completely. Drug treatment programs in Europe often report more favourable outcomes than those in the USA because the criteria for measuring success are functional rather than abstinence-based. The supporters of programs with total abstinence from drugs as a goal believe that enabling further drug use just means prolonged drug use and risks an increase in addiction and complications from addiction.

It is occasionally sometimes difficult to convince people with substance dependencies to engage in any form of treatment. Family Interventions have been highly successful in helping these people accept help they need.

Residential

Residential drug treatment can be broadly divided into two camps: 12 step programs or Therapeutic Communities. 12 step programs have the advantage of coming with an instant social support network, though some find the spiritual context not to their taste. In the UK drug treatment is generally moving towards a more integrated approach with rehabs offering a variety of approaches. These other programs may use a Cognitive-Behavioral Therapy approach, such as SMART Recovery
SMART Recovery
SMART Recovery is an international non-profit organization which provides assistance to individuals seeking abstinence from addictive behaviors. The approach used is secular and science-based using non-confrontational motivational, behavioral and cognitive methods...

, that looks at the relationship between thoughts, feelings and behaviors, recognizing that a change in any of these areas can affect the whole. CBT sees addiction as a behavior rather than a disease and subsequently curable, or rather, unlearnable. CBT programs recognize that for some individuals controlled use is a more realistic possibility.

One of many recovery methods is the 12 step recovery program
Twelve-step program
A Twelve-Step Program is a set of guiding principles outlining a course of action for recovery from addiction, compulsion, or other behavioral problems...

, with prominent examples including Alcoholics Anonymous
Alcoholics Anonymous
Alcoholics Anonymous is an international mutual aid movement which says its "primary purpose is to stay sober and help other alcoholics achieve sobriety." Now claiming more than 2 million members, AA was founded in 1935 by Bill Wilson and Dr. Bob Smith in Akron, Ohio...

, Narcotics Anonymous
Narcotics Anonymous
Narcotics Anonymous is a twelve-step program modeled after Alcoholics Anonymous describing itself as a "fellowship or society of men and women for whom drugs had become a major problem," and it is the second-largest 12-step organization...

, Drug Addicts Anonymous and Pills Anonymous
Pills Anonymous
Pills Anonymous is a twelve-step program for people who seek recovery from prescription drug addiction. PA is patterned very closely after Alcoholics Anonymous, although the two groups are not affiliated....

. They are commonly known and used for a variety of addictions for the individual addicted and the family of the individual. Substance-abuse rehabilitation (or "rehab") centers offer a residential treatment program for some of more seriously addicted in order to isolate the patient from drugs and interactions with other users and dealers. Outpatient clinics usually offer a combination of individual counseling and group counseling. Frequently a physician or psychiatrist will assist, with prescriptions
Pharmacology
Pharmacology is the branch of medicine and biology concerned with the study of drug action. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function...

, the side effects of the addiction. Medications can help immensely with anxiety and insomnia, can treat underlying mental disorders (cf. Self-medication hypothesis, Khantzian 1997) such as (manic-)depression, and can help reduce or eliminate withdrawal symptomology when withdrawing from physiologically addictive drugs. Some examples are using benzodiazepines for alcohol detoxification, which prevents delirium tremens
Delirium tremens
Delirium tremens is an acute episode of delirium that is usually caused by withdrawal from alcohol, first described in 1813...

 and complications; using a slow taper of benzodiazepines or a taper of phenobarbital
Phenobarbital
Phenobarbital or phenobarbitone is a barbiturate, first marketed as Luminal by Friedr. Bayer et comp. It is the most widely used anticonvulsant worldwide, and the oldest still commonly used. It also has sedative and hypnotic properties but, as with other barbiturates, has been superseded by the...

, sometimes including another antiepileptic agent such as gabapentin
Gabapentin
Gabapentin is a pharmaceutical drug, specifically a GABA analogue. It was originally developed for the treatment of epilepsy, and currently is also used to relieve neuropathic pain...

, pregabalin
Pregabalin
Pregabalin is an anticonvulsant drug used for neuropathic pain and as an adjunct therapy for partial seizures with or without secondary generalization in adults. It has also been found effective for generalized anxiety disorder and is approved for this use in the European Union. It was designed...

, or valproate, for withdrawal from barbiturates or benzodiazepines; using drugs such as baclofen
Baclofen
Baclofen is a derivative of gamma-aminobutyric acid . It is primarily used to treat spasticity and is under investigation for the treatment of alcoholism....

 to reduce cravings and propensity for relapse amongst addicts to any drug, especially effective in stimulant users, and alcoholics (in which it is nearly as effective as benzodiazepines in preventing complications); using clonidine
Clonidine
Clonidine is a sympatholytic medication used to treat medical conditions, such as high blood pressure, some pain conditions, ADHD and anxiety/panic disorder...

, a benzodiazepine
Benzodiazepine
A benzodiazepine is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring...

, and loperamide
Loperamide
Loperamide , a synthetic piperidine derivative, is an opioid drug used against diarrhea resulting from gastroenteritis or inflammatory bowel disease. In most countries it is available generically and under brand names such as Lopex, Imodium, Dimor, Fortasec, and Pepto Diarrhea Control...

 for opioid detoxification, for first-time users or those who wish to attempt an abstinence-based recovery (90% of opioid users relapse to active addiction within 8 months and/or are "multiple relapse patients"); or replacing an opioid that is interfering with or destructive to a user's life, such as illicitly-obtained heroin, Dilaudid, or oxycodone
Oxycodone
Oxycodone is an opioid analgesic medication synthesized from opium-derived thebaine. It was developed in 1916 in Germany, as one of several new semi-synthetic opioids in an attempt to improve on the existing opioids: morphine, diacetylmorphine , and codeine.Oxycodone oral medications are generally...

, with an opioid that can be administered legally, reduces or eliminates drug cravings, and does not produce a high, such as methadone
Methadone
Methadone is a synthetic opioid, used medically as an analgesic and a maintenance anti-addictive for use in patients with opioid dependency. It was developed in Germany in 1937...

 or buprenorphine
Buprenorphine
Buprenorphine is a semi-synthetic opioid that is used...

 - opioid replacement therapy
Opiate replacement therapy
Opioid replacement therapy is the medical procedure of replacing an illegal opioid drug such as heroin with a longer acting but less euphoric opioid, usually methadone or buprenorphine, that is taken under medical supervision. In some countries patients may be treated with slow-release morphine...

 - which is the gold standard for treatment of opioid dependence in developed countries, reducing the risk and cost to both user and society more effectively than any other treatment modality (for opioid dependence), and shows the best short-term and long-term gains for the user, with the greatest longevity, least risk of fatality, greatest quality of life, and lowest risk of relapse and/or legal issues including arrest and incarceration.

In a survey of treatment providers from three separate institutions (the National Association of Alcoholism and Drug Abuse Counselors, Rational Recovery Systems and the Society of Psychologists in Addictive Behaviors) measuring the treatment provider's responses on the Spiritual Belief Scale (a scale measuring belief in the four spiritual characteristics AA identified by Ernest Kurtz); the scores were found to explain 41% of the variance
Analysis of variance
In statistics, analysis of variance is a collection of statistical models, and their associated procedures, in which the observed variance in a particular variable is partitioned into components attributable to different sources of variation...

 in the treatment provider's responses on the Addiction Belief Scale (a scale measuring adherence to the disease model
Disease model of addiction
The disease model of addiction describes an addiction as a lifelong disease involving biologic and environmental sources of origin. The traditional medical model of disease requires only that an abnormal condition be present that causes discomfort, dysfunction, or distress to the individual...

 or the free-will model addiction).

Anti-addictive drugs

Other forms of treatment include replacement drugs such as suboxone/subutex (both containing the active ingredient buprenorphine
Buprenorphine
Buprenorphine is a semi-synthetic opioid that is used...

),and methadone
Methadone
Methadone is a synthetic opioid, used medically as an analgesic and a maintenance anti-addictive for use in patients with opioid dependency. It was developed in Germany in 1937...

, are all used as substitutes for illicit opiate drugs. Although these drugs perpetuate physical dependence, the goal of opiate maintenance is to provide a clinically supervised, stable dose of a particular opioid in order to provide a measure of control to both pain and cravings. This provides a chance for the addict to function normally and to reduce the negative consequences associated with obtaining sufficient quantities of controlled substances illicitly, by both reducing opioid cravings and withdrawal symptomology. Once a prescribed dosage is stabilized, treatment enters maintenance or tapering phases. In the United States, opiate replacement therapy is tightly regulated in methadone clinics and under the DATA 2000 legislation. In some countries, other opioid derivatives such as levomethadyl acetate, dihydrocodeine
Dihydrocodeine
Dihydrocodeine, also called DHC, Drocode, Paracodeine and Parzone and known by the brand names of Synalgos DC, Panlor DC, Panlor SS, Contugesic, New Bron Solution-ACE, Huscode, Drocode, Paracodin, Codidol, Didor Continus, Dicogesic, Codhydrine, Dekacodin, DH-Codeine,...

, dihydroetorphine
Dihydroetorphine
Dihydroetorphine was developed by K.W.Bentley at McFarlan-Smith in the 1960s and is a potent analgesic drug , which is used mainly in China...

 and even heroin are used as substitute drugs for illegal street opiates, with different drugs being used depending on the needs of the individual patient. Baclofen
Baclofen
Baclofen is a derivative of gamma-aminobutyric acid . It is primarily used to treat spasticity and is under investigation for the treatment of alcoholism....

 has been shown successful in attenuating cravings for most drugs of abuse - stimulants, ethanol, and opioids - and also attenuates the actual withdrawal syndrome of ethanol. Many patients have stated they "became indifferent to alcohol" or "indifferent to cocaine" overnight after starting baclofen therapy. It is possible that one of the best, albeit relatively unexplored, treatment modalities for opioid addiction - notoriously the most difficult addiction to treat (and to recover from), having relapse rates of around 60% at four weeks and 97% at twelve months if not on maintenance therapy with a mu-opioid agonist - would be to combine an opioid maintenance agent, such as methadone or buprenorphine, to block withdrawal symptomology, with baclofen, to attenuate cravings and the desire to use, in people who find that they are still using or still craving drugs while on methadone or buprenorphine maintenance.

Substitute drugs for other forms of drug dependence have historically been less successful than opioid substitute treatment, but some limited success has been seen with drugs such as dextroamphetamine
Dextroamphetamine
Dextroamphetamine is a psychostimulant drug which is known to produce increased wakefulness and focus as well as decreased fatigue and decreased appetite....

 to treat stimulant addiction, and clomethiazole
Clomethiazole
Clomethiazole is a sedative and hypnotic originally developed by Hoffmann-Le Roche in the 1930s. The drug is used in treating and preventing symptoms of acute alcohol withdrawal....

 to treat alcohol addiction. Bromocriptine
Bromocriptine
Bromocriptine , an ergoline derivative, is a dopamine agonist that is used in the treatment of pituitary tumors, Parkinson's disease , hyperprolactinaemia, neuroleptic malignant syndrome, and type 2 diabetes.- Indications :Amenorrhea, female infertility, galactorrhea, hypogonadism, and acromegaly...

 and desipramine
Desipramine
Desipramine is a tricyclic antidepressant . It inhibits the reuptake of norepinephrine and to a lesser extent serotonin. It is used to treat depression, but not considered a first line treatment since the introduction of SSRI antidepressants...

 have been reported to be effective for treatment of cocaine but not amphetamine addiction.

Other pharmacological treatments for alcohol addiction include drugs like naltrexone
Naltrexone
Naltrexone is an opioid receptor antagonist used primarily in the management of alcohol dependence and opioid dependence. It is marketed in generic form as its hydrochloride salt, naltrexone hydrochloride, and marketed under the trade names Revia and Depade...

, disulfiram
Disulfiram
Disulfiram is a drug discovered in the 1920s and used to support the treatment of chronic alcoholism by producing an acute sensitivity to alcohol. Trade names for disulfiram in different countries are Antabuse and Antabus manufactured by Odyssey Pharmaceuticals...

, acamprosate
Acamprosate
Acamprosate, also known as N-acetyl homotaurine and by the brand name Campral, is a drug used for treating alcohol dependence.Acamprosate is thought to stabilize the chemical balance in the brain that would otherwise be disrupted by alcoholism, possibly by blocking glutamatergic...

 and topiramate
Topiramate
Topiramate is an anticonvulsant drug. It was originally produced by Ortho-McNeil Neurologics and Noramco, Inc., both divisions of the Johnson & Johnson Corporation. This medication was discovered in 1979 by Bruce E. Maryanoff and Joseph F. Gardocki during their research work at McNeil...

, but rather than substituting for alcohol, these drugs are intended to reduce the desire to drink, either by directly reducing cravings as with acamprosate and topiramate, or by producing unpleasant effects when alcohol is consumed, as with disulfiram. These drugs can be effective if treatment is maintained, but compliance can be an issue as alcoholic patients often forget to take their medication, or discontinue use because of excessive side effects. Additional drugs acting on glutamate neurotransmission such as modafinil
Modafinil
Modafinil is an analeptic drug manufactured by Cephalon, and is approved by the U.S. Food and Drug Administration for the treatment of narcolepsy, shift work sleep disorder, and excessive daytime sleepiness associated with obstructive sleep apnea...

, lamotrigine
Lamotrigine
Lamotrigine, marketed in the US and most of Europe as Lamictal by GlaxoSmithKline, is an anticonvulsant drug used in the treatment of epilepsy and bipolar disorder. It is also used as an adjunct in treating depression, though this is considered off-label usage...

, gabapentin
Gabapentin
Gabapentin is a pharmaceutical drug, specifically a GABA analogue. It was originally developed for the treatment of epilepsy, and currently is also used to relieve neuropathic pain...

 and memantine have also been proposed for use in treating addiction to alcohol and other drugs.

Opioid antagonists such as naltrexone
Naltrexone
Naltrexone is an opioid receptor antagonist used primarily in the management of alcohol dependence and opioid dependence. It is marketed in generic form as its hydrochloride salt, naltrexone hydrochloride, and marketed under the trade names Revia and Depade...

 and nalmefene
Nalmefene
Nalmefene is an opioid receptor antagonist developed in the early 1970s, and used primarily in the management of alcohol dependence, and also has been investigated for the treatment of other addictions such as pathological gambling and addiction to shopping.Nalmefene is an opiate derivative...

 have also been used successfully in the treatment of alcohol addiction, which is often particularly challenging to treat. Some have also attempted to use these drugs for maintenance treatment of former opiate addicts with little success. They cannot be started until the patient has been abstinent for an extended period - unlikely with opioid addicts who are not on maintenance with a full or partial mu-opioid agonist - or they will trigger acute opioid withdrawal symptoms. No study has found them to be efficacious treatments in preventing relapse. They do nothing to block craving, and block endorphin and enkephalin, two natural neurotransmitters that regulate one's sense of well-being. An addict must discontinue the drug for just eighteen hours in order to use again.

Treatment of stimulant
Stimulant
Stimulants are psychoactive drugs which induce temporary improvements in either mental or physical function or both. Examples of these kinds of effects may include enhanced alertness, wakefulness, and locomotion, among others...

 addiction can often be difficult, with substitute drugs often being ineffective, although newer drugs such as nocaine
Nocaine
-CPCA is a stimulant drug similar in structure to RTI-31, but lacking the two-carbon bridge of the tropane skeleton This compound was first developed as a substitute agent for cocaine.Since this time a large number of substituted phenylpiperidine derivatives have been discovered, hybridizing the...

, vanoxerine
Vanoxerine
Vanoxerine is a piperazine derivative which is a potent and selective DRI. GBR-12909 binds to the target site on the DAT ~ 500 times more strongly than cocaine, but simultaneously inhibits the release of dopamine...

 and modafinil
Modafinil
Modafinil is an analeptic drug manufactured by Cephalon, and is approved by the U.S. Food and Drug Administration for the treatment of narcolepsy, shift work sleep disorder, and excessive daytime sleepiness associated with obstructive sleep apnea...

 may have more promise in this area, as well as the GABAB agonist baclofen
Baclofen
Baclofen is a derivative of gamma-aminobutyric acid . It is primarily used to treat spasticity and is under investigation for the treatment of alcoholism....

. Another strategy that has recently been successfully trialled used a combination of the benzodiazepine
Benzodiazepine
A benzodiazepine is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring...

 antagonist flumazenil
Flumazenil
Flumazenil is a benzodiazepine antagonist available for injection only, and the only benzodiazepine receptor antagonist on the market today.It was first introduced in 1987 by Hoffmann-La Roche under the trade name Anexate, but only approved by...

 with hydroxyzine
Hydroxyzine
Hydroxyzine is a first-generation antihistamine of the diphenylmethane and piperazine classes. It was first synthesized by Union Chimique Belge in 1956 and was marketed by Pfizer in the United States later the same year, and is still in widespread use today....

 and gabapentin
Gabapentin
Gabapentin is a pharmaceutical drug, specifically a GABA analogue. It was originally developed for the treatment of epilepsy, and currently is also used to relieve neuropathic pain...

 for the treatment of methamphetamine
Methamphetamine
Methamphetamine is a psychostimulant of the phenethylamine and amphetamine class of psychoactive drugs...

 addiction.

Another area in which drug treatment has been widely used is in the treatment of nicotine
Nicotine
Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...

 addiction. Various drugs have been used for this purpose such as bupropion
Bupropion
Bupropion is an atypical antidepressant and smoking cessation aid. The drug is a non-tricyclic antidepressant and differs from most commonly prescribed antidepressants such as SSRIs, as its primary pharmacological action is thought to be norepinephrine-dopamine reuptake inhibition...

, mecamylamine
Mecamylamine
Mecamylamine is a nonselective and noncompetitive antagonist of the nicotinic acetylcholine receptors that was introduced in the 1950s as an antihypertensive agent.- Uses :...

 and the more recently developed varenicline. The cannaboinoid antagonist rimonabant
Rimonabant
Rimonabant is an anorectic antiobesity drug that has been withdrawn from the market. It is an inverse agonist for the cannabinoid receptor CB1...

 has also been trialled for treatment of nicotine addiction but has not been widely adopted for this purpose.

Ibogaine
Ibogaine
Ibogaine is a naturally occurring psychoactive substance found in a number of plants, principally in a member of the Apocynaceae family known as Iboga . A hallucinogen with both psychedelic and dissociative properties, the substance is banned in some countries; in other countries it is being used...

 is a hallucinogen (psychotomimetic) that some claim interrupts addiction and reduces or eliminates withdrawal syndromes, specifically in regards to opioids. Its mechanism of action is unknown, but likely linked to nAchR α3ß4 antagonism. In one animal trial, it was shown to slightly reduce self-administration of cocaine. Another uncontrolled trial showed it reduced tremor by a mild to moderate degree during morphine withdrawal in rats. These finding can not be extrapolated to human beings with any certainty. Research is complicated by the fact that ibogaine is illegal
Prohibition (drugs)
The prohibition of drugs through sumptuary legislation or religious law is a common means of attempting to prevent drug use. Prohibition of drugs has existed at various levels of government or other authority from the Middle Ages to the present....

 in many developed countries, and a Schedule I substance in the US, and as a result no controlled human trials have ever been performed. A semi-synthetic analogue of ibogaine, 18-methoxycoronaridine
18-Methoxycoronaridine
-18-Methoxycoronaridine is a derivative of ibogaine invented in 1996 by the research team around the pharmacologist Stanley D. Glick from the Albany Medical College and the chemist Martin E. Kuehne from the University of Vermont...

 was developed, in an attempt to reduce the toxic (ibogaine is significantly cardiotoxic, and several deaths have been reported from its use; because of its illegal, underground nature, it is impossible to know how toxic the drug is) and psychotomimetic effects of the drug.

Behavioral programming

Behavioral programming is considered critical to helping those with addictions achieve abstinence. From the applied behavior analysis
Applied Behavior Analysis
Applied behavior analysis is a science that involves using modern behavioral learning theory to modify behaviors. Behavior analysts reject the use of hypothetical constructs and focus on the observable relationship of behavior to the environment...

 literature and the behavioral psychology literature several evidenced based intervention programs have emerged (1) behavioral maritial therapy; (2) community reinforcement approach; (3) cue exposure therapy; and (4) contingency management strategies. In addition, the same author suggest that Social skills training adjunctive to inpatient treatment of alcohol dependence is probably efficacious. Community reinforcement has both efficacy and effectiveness data. In addition, behavioral treatment such as community reinforcement and family training (CRAFT) have helped family members to get their loved ones into treatment.

Alternative therapies

Alternative therapies, such as acupuncture
Acupuncture
Acupuncture is a type of alternative medicine that treats patients by insertion and manipulation of solid, generally thin needles in the body....

, are used by some practitioners to alleviate the symptoms of drug addiction. In 1997, the American Medical Association (AMA) adopted as policy the following statement after a report on a number of alternative therapies including acupuncture:
There is little evidence to confirm the safety or efficacy of most alternative therapies. Much of the information currently known about these therapies makes it clear that many have not been shown to be efficacious. Well-designed, stringently controlled research should be done to evaluate the efficacy of alternative therapies.


Acupuncture has been shown to be no more effective than control treatments in the treatment of opiate dependence. Acupuncture, acupressure, laser therapy and electrostimulation have no demonstrated efficacy for smoking cessation.
Online Websites: Online websites have been a great resource to aid in helping people to overcome their addictions. These websites act as ways for struggling addicts, family members of addicts, and people who are in the recovery stage to confide in each other (anonymously if they so choose). They provide an alternative way for these people to seek help, support and information. Sites typically include chat rooms,forums and blogs for members to interact.

Epidemiology

The most common drug addictions are to legal substances such as:
  • Nicotine
    Nicotine
    Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...

     in the form of tobacco
    Tobacco
    Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...

    , particularly cigarette
    Cigarette
    A cigarette is a small roll of finely cut tobacco leaves wrapped in a cylinder of thin paper for smoking. The cigarette is ignited at one end and allowed to smoulder; its smoke is inhaled from the other end, which is held in or to the mouth and in some cases a cigarette holder may be used as well...

    s
  • Alcohol
    Alcohol
    In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

  • Caffeine
    Caffeine
    Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...


History

The phenomenon
Phenomenon
A phenomenon , plural phenomena, is any observable occurrence. Phenomena are often, but not always, understood as 'appearances' or 'experiences'...

 of drug addiction has occurred to some degree throughout recorded history
History
History is the discovery, collection, organization, and presentation of information about past events. History can also mean the period of time after writing was invented. Scholars who write about history are called historians...

 (see "Opium
Opium
Opium is the dried latex obtained from the opium poppy . Opium contains up to 12% morphine, an alkaloid, which is frequently processed chemically to produce heroin for the illegal drug trade. The latex also includes codeine and non-narcotic alkaloids such as papaverine, thebaine and noscapine...

"). Modern agricultural
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

 practices, improvements in access to drugs, advancements in biochemistry
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...

, and dramatic increases in the recommendation of drug usage by clinical practitioners have exacerbated the problem significantly in the 20th century. Improved means of active biological agent manufacture and the introduction of synthetic compounds, such as methamphetamine
Methamphetamine
Methamphetamine is a psychostimulant of the phenethylamine and amphetamine class of psychoactive drugs...

 are also factors contributing to drug addiction.

Legislation

Depending on the jurisdiction
Jurisdiction
Jurisdiction is the practical authority granted to a formally constituted legal body or to a political leader to deal with and make pronouncements on legal matters and, by implication, to administer justice within a defined area of responsibility...

, addictive drugs may be legal only as part of a government sponsored study, illegal to use for any purpose, illegal to sell, or even illegal to merely possess.

Most countries have legislation which brings various drugs and drug-like substances
Chemical substance
In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e. without breaking chemical bonds. They can be solids, liquids or gases.Chemical substances are...

 under the control of licensing systems. Typically this legislation covers any or all of the opiates, amphetamines, cannabinoids, cocaine, barbiturates, benzodiazepines, anesthetics, hallucinogenics, derivatives and a variety of more modern synthetic drugs. Unlicensed production, supply or possession is a criminal offence.

Usually, however, drug classification under such legislation is not related simply to addictiveness. The substances covered often have very different addictive properties. Some are highly prone to cause physical dependency, while others rarely cause any form of compulsive need whatsoever. Also, under legislation specifically about drugs, alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

, caffeine
Caffeine
Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...

 and nicotine
Nicotine
Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...

 are not usually included.

Although the legislation may be justifiable on moral or public health grounds, it can make addiction or dependency a much more serious issue for the individual: reliable supplies of a drug become difficult to secure, and the individual becomes vulnerable to both criminal abuse and legal punishment.

It is unclear whether laws against illegal drug use do anything to stem usage and dependency. In jurisdictions where addictive drugs are illegal, they are generally supplied by drug dealers, who are often involved with organized crime
Organized crime
Organized crime or criminal organizations are transnational, national, or local groupings of highly centralized enterprises run by criminals for the purpose of engaging in illegal activity, most commonly for monetary profit. Some criminal organizations, such as terrorist organizations, are...

. Even though the cost of producing most illegal addictive substances is very low, their illegality combined with the addict's need permits the seller to command a premium price, often hundreds of times the production cost. As a result, addicts sometimes turn to crime to support their habit.

See also

  • Addictive personality
    Addictive personality
    An addictive personality refers to a particular set of personality traits that make an individual predisposed to addictions. People who are substance dependent are characterized by: a physical or psychological dependency that negatively impacts the quality of life...

  • Drug and Alcohol Dependence (journal)
  • Physical dependence
    Physical dependence
    Physical dependence refers to a state resulting from chronic use of a drug that has produced tolerance and where negative physical symptoms of withdrawal result from abrupt discontinuation or dosage reduction...

  • Risk factors in pregnancy
    Risk factors in pregnancy
    Factors increasing the risk of pregnancy beyond the normal level of risk may be present in a woman's medical profile either before she becomes pregnant or during the pregnancy. These pre-existing factors may relate to physical and/or mental health, and/or to social issues, or a combination...

  • Self medication
    Self Medication
    Self Medication is an album by the New York City ska band The Slackers. It was released on Indication Records in 2008 .-Track listing:# "Every Day Is Sunday" – 2:35# "Don't You Want a Man" – 3:30...

  • Substance abuse
    Substance abuse
    A substance-related disorder is an umbrella term used to describe several different conditions associated with several different substances .A substance related disorder is a condition in which an individual uses or abuses a...

  • Faith-head
    Faith-head
    Faith-head is a pejorative term used to describe an overly religious person. The term is usually used by irreligious people as a derogotary slur to refer to religious people...



Questionnaires
  • Alcohol Use Disorders Identification Test
    Alcohol Use Disorders Identification Test
    The Alcohol Use Disorders Identification Test is a simple ten-question test developed by the World Health Organization to determine if a person's alcohol consumption may be harmful. The test was designed to be used internationally, and was validated in a study using patients from six countries...

  • CAGE questionnaire
    CAGE questionnaire
    The CAGE questionnaire, the name of which is an acronym of its four questions, is a widely used method of screening for alcoholism.The CAGE questionnaire, among other methods, has been extensively validated for use in identifying alcoholism...

  • CRAFFT Screening Test
    CRAFFT Screening Test
    CRAFFT Screening Test is a short, self-administered behavioural health screening tool developed to screen adolescents for high risk alcohol and other drug use disorders simultaneously. It is considered an effective screening tool intended to assess whether further assessment is warranted...

  • Paddington Alcohol Test
    Paddington alcohol test
    The Paddington Alcohol Test was first published in the Journal of Accident and Emergency Medicine in 1996. It was designed to identify alcohol-related problems amongst those attending Accident and Emergency departments...

  • Severity of Alcohol Dependence Questionnaire
    Severity of Alcohol Dependence Questionnaire
    The Severity of Alcohol Dependence Questionnaire is a 20 item clinical screening tool designed to measure the presence and level of alcohol dependence.It is divided into 5 sections:* Physical withdrawal symptoms* Affective withdrawal symptoms...



External links

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