Chemical imbalance
Encyclopedia
Chemical imbalance is one hypothesis about the cause of mental illness
. Other causes that are debated include psychological and social causes.
The basic concept is that neurotransmitter
imbalances within the brain
are the main causes of psychiatric conditions and that these conditions can be improved with medication
which corrects these imbalances. The phrase originated from the scientific study of brain chemistry. In the 1950s the monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants were accidentally discovered to be effective in the treatment of depression
. These findings and other supporting evidence led Joseph Schildkraut to publish his paper called "The Catecholamine Hypothesis of Affective Disorders" in 1965. Schildkraut associated low levels of neurotransmitter
s with depression.
Research into other mental illnesses such as schizophrenia
also found that too much activity of certain neurotransmitter
s such as dopamine was correlated to these disorders. In the scientific community this hypothesis has been referred to as the "Monoamine hypothesis". This hypothesis has been a major focus of research in the fields pathophysiology
and pharmacotherapy
for over 25 years and led to the development of new classes of drugs such as SSRIs (selective-serotonin reuptake inhibitors).
This conceptual framework has been challenged within the scientific community, though no other demonstrably superior hypothesis has emerged. While the hypothesis has been shown to be simplistic and lacking, there is sufficient evidence to consider it as a useful heuristic in the aiding of our understanding of brain chemistry and explaining pharmacotherapy
.
Wayne Goodman, Chair of the US Food and Drug Administration Psychopharmacological Advisory Committee, has described the serotonergic theory of depression as a "useful metaphor" for understanding depression
, though not one that he uses with his own psychiatric patients. Recently, psychiatrist Peter Kramer stated that the serotonin theory of depression had been declared dead prematurely. Kramer argues that recent scientific research actually shows a definitive role for serotonin deficiency in depression. An analysis of the studies Kramer cites argues that such statements are premature.
is caused by the underactivity in the brain of monoamines, such as dopamine, serotonin, and norepinephrine.
In the 1950s the monoamine oxidase inhibitor
s (MAOIs) and tricyclic antidepressants were accidentally discovered to be effective in the treatment of depression. These findings and other supporting evidence led Joseph Schildkraut to publish his paper called "The Catecholamine Hypothesis of Affective Disorders" in 1965. Schildkraut associated low levels of neurotransmitters with depression. Research into other mental impairments such as schizophrenia
also found that too little activity of certain neurotransmitters were connected to these disorders.
The hypothesis has been a major focus of research in the fields pathophysiology
and pharmacotherapy
for over 25 years. and led to the development of new classes of drugs such as SSRIs (selective serotonin reuptake inhibitor
s).
, particular focus has been placed upon the function of dopamine in the mesolimbic pathway
of the brain. This focus largely resulted from the accidental finding that a drug group which blocks dopamine function, known as the phenothiazines, could reduce psychotic symptoms. It is also supported by the fact that amphetamine
s, which trigger the release of dopamine may exacerbate the psychotic symptoms in schizophrenia.
An influential theory, known as the Dopamine hypothesis of schizophrenia
, proposed that a malfunction involving dopamine pathways was the cause of (the positive symptoms of) schizophrenia. This theory is now thought to be overly simplistic as a complete explanation, partly because newer antipsychotic medication (called atypical antipsychotic
medication) can be equally effective as older medication (called typical antipsychotic
medication), but also affects serotonin
function and may have slightly less of a dopamine
blocking effect.
continue to promote drugs like Zoloft with advertisements asserting that mental illness may be due to chemical imbalances in the brain, and that their drugs work to "correct" this imbalance. Most academics believe that the advertisements are oversimplified and don't fully explain what is happening.
Chemical imbalances theories do not presume individual laboratory tests be obtained from a patient at the time of prescription, such as one would expect in the analogy to physical medicine. For example, someone suffering from schizophrenia is not given haloperidol
on the basis of a laboratory test which shows that his or her dopamine level is too high.
Chemical imbalances theories distinguish, between "side" and "main" drug effects in recording the response to the drug. "Side" effects are considered to be simple, direct, predictable, allowable effects which are merely "physical" but do include often flattened affect and memory, emotive and cognitive effects. These drug effects may then be cited capriciously as further evidence to confirm the diagnosis as correct, confusing cause and effect.
When "improvement" is measured in industry research studies, attention is given only to the "main" effect—typically a complex, indirect, interpersonal, perceptual, cultural change, thereby confusing cause with coincidence. There does not exist in chemical imbalance theories, effectiveness measures using standard social networks and associated tests before and after drug administration.
Chemical imbalance theories predominate in "streamline" public sector medicine for lower social class
and homeless persons, where drugs constitute the only form of treatment. There is much wishful thinking in attribution of drug effect, particularly in cases like schizophrenia
, where there no longer exists a patient [non-drug user] control group available.
One criticism while not outright rejecting the theory is that it has been scientifically proven that things other than drugs can influence brain chemistry. Exercise releases endorphin
s. Even our own thoughts change our brain chemistry. These natural methods of changing brain chemicals are claimed by critics to be preferable to drugs since drugs have side effects. Furthermore, some psychiatric drugs might alter the mind by disabling mood
s and emotion
s not just in circumstances where they're a problem but in circumstances where they're appropriate or even beneficial as well while natural ways to change brain chemistry can be used as needed.
Mental illness
A mental disorder or mental illness is a psychological or behavioral pattern generally associated with subjective distress or disability that occurs in an individual, and which is not a part of normal development or culture. Such a disorder may consist of a combination of affective, behavioural,...
. Other causes that are debated include psychological and social causes.
The basic concept is that neurotransmitter
Neurotransmitter
Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...
imbalances within the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
are the main causes of psychiatric conditions and that these conditions can be improved with medication
Medication
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
which corrects these imbalances. The phrase originated from the scientific study of brain chemistry. In the 1950s the monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants were accidentally discovered to be effective in the treatment of depression
Clinical depression
Major depressive disorder is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities...
. These findings and other supporting evidence led Joseph Schildkraut to publish his paper called "The Catecholamine Hypothesis of Affective Disorders" in 1965. Schildkraut associated low levels of neurotransmitter
Neurotransmitter
Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...
s with depression.
Research into other mental illnesses such as schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
also found that too much activity of certain neurotransmitter
Neurotransmitter
Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...
s such as dopamine was correlated to these disorders. In the scientific community this hypothesis has been referred to as the "Monoamine hypothesis". This hypothesis has been a major focus of research in the fields pathophysiology
Pathophysiology
Pathophysiology is the study of the changes of normal mechanical, physical, and biochemical functions, either caused by a disease, or resulting from an abnormal syndrome...
and pharmacotherapy
Pharmacotherapy
Pharmacotherapy is the treatment of disease through the administration of drugs. As such, it is considered part of the larger category of therapy....
for over 25 years and led to the development of new classes of drugs such as SSRIs (selective-serotonin reuptake inhibitors).
This conceptual framework has been challenged within the scientific community, though no other demonstrably superior hypothesis has emerged. While the hypothesis has been shown to be simplistic and lacking, there is sufficient evidence to consider it as a useful heuristic in the aiding of our understanding of brain chemistry and explaining pharmacotherapy
Pharmacotherapy
Pharmacotherapy is the treatment of disease through the administration of drugs. As such, it is considered part of the larger category of therapy....
.
Wayne Goodman, Chair of the US Food and Drug Administration Psychopharmacological Advisory Committee, has described the serotonergic theory of depression as a "useful metaphor" for understanding depression
Clinical depression
Major depressive disorder is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities...
, though not one that he uses with his own psychiatric patients. Recently, psychiatrist Peter Kramer stated that the serotonin theory of depression had been declared dead prematurely. Kramer argues that recent scientific research actually shows a definitive role for serotonin deficiency in depression. An analysis of the studies Kramer cites argues that such statements are premature.
Monoamine hypothesis
The Monoamine hypothesis is a biological theory stating that depressionClinical depression
Major depressive disorder is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities...
is caused by the underactivity in the brain of monoamines, such as dopamine, serotonin, and norepinephrine.
In the 1950s the monoamine oxidase inhibitor
Monoamine oxidase inhibitor
Monoamine oxidase inhibitors are a class of antidepressant drugs prescribed for the treatment of depression. They are particularly effective in treating atypical depression....
s (MAOIs) and tricyclic antidepressants were accidentally discovered to be effective in the treatment of depression. These findings and other supporting evidence led Joseph Schildkraut to publish his paper called "The Catecholamine Hypothesis of Affective Disorders" in 1965. Schildkraut associated low levels of neurotransmitters with depression. Research into other mental impairments such as schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
also found that too little activity of certain neurotransmitters were connected to these disorders.
The hypothesis has been a major focus of research in the fields pathophysiology
Pathophysiology
Pathophysiology is the study of the changes of normal mechanical, physical, and biochemical functions, either caused by a disease, or resulting from an abnormal syndrome...
and pharmacotherapy
Pharmacotherapy
Pharmacotherapy is the treatment of disease through the administration of drugs. As such, it is considered part of the larger category of therapy....
for over 25 years. and led to the development of new classes of drugs such as SSRIs (selective serotonin reuptake inhibitor
Selective serotonin reuptake inhibitor
Selective serotonin re-uptake inhibitors or serotonin-specific reuptake inhibitor are a class of compounds typically used as antidepressants in the treatment of depression, anxiety disorders, and some personality disorders. The efficacy of SSRIs is disputed...
s).
Dopamine hypothesis
In studying the causes of schizophreniaSchizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
, particular focus has been placed upon the function of dopamine in 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...
of the brain. This focus largely resulted from the accidental finding that a drug group which blocks dopamine function, known as the phenothiazines, could reduce psychotic symptoms. It is also supported by the fact that 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, which trigger the release of dopamine may exacerbate the psychotic symptoms in schizophrenia.
An influential theory, known as the Dopamine hypothesis of schizophrenia
Dopamine hypothesis of schizophrenia
The dopamine hypothesis of schizophrenia or the dopamine hypothesis of psychosis is a model attributing symptoms of schizophrenia to a disturbed and hyperactive dopaminergic signal transduction. The model draws evidence from the observation that a large number of antipsychotics have...
, proposed that a malfunction involving dopamine pathways was the cause of (the positive symptoms of) schizophrenia. This theory is now thought to be overly simplistic as a complete explanation, partly because newer antipsychotic medication (called atypical antipsychotic
Atypical antipsychotic
The atypical antipsychotics are a group of antipsychotic tranquilizing drugs used to treat psychiatric conditions. Some atypical antipsychotics are FDA approved for use in the treatment of schizophrenia...
medication) can be equally effective as older medication (called typical antipsychotic
Typical antipsychotic
Typical antipsychotics are a class of antipsychotic drugs first developed in the 1950s and used to treat psychosis...
medication), but also affects 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...
function and may have slightly less of a 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...
blocking effect.
Criticisms
According to critics, the chemical imbalance hypothesis has been overpromoted and continues to be advanced as factual by pharmaceutical companies. They believe the general population and many journalists have accepted this hypothesis into their understanding of mental illness uncritically. They have pointed to the lack of an established chemical balance (without which, they claim, the notion of an "imbalance" is meaningless). Certain pharmaceutical companies such as PfizerPfizer
Pfizer, Inc. is an American multinational pharmaceutical corporation. The company is based in New York City, New York with its research headquarters in Groton, Connecticut, United States...
continue to promote drugs like Zoloft with advertisements asserting that mental illness may be due to chemical imbalances in the brain, and that their drugs work to "correct" this imbalance. Most academics believe that the advertisements are oversimplified and don't fully explain what is happening.
Chemical imbalances theories do not presume individual laboratory tests be obtained from a patient at the time of prescription, such as one would expect in the analogy to physical medicine. For example, someone suffering from schizophrenia is not given haloperidol
Haloperidol
Haloperidol is a typical antipsychotic. It is in the butyrophenone class of antipsychotic medications and has pharmacological effects similar to the phenothiazines....
on the basis of a laboratory test which shows that his or her dopamine level is too high.
Chemical imbalances theories distinguish, between "side" and "main" drug effects in recording the response to the drug. "Side" effects are considered to be simple, direct, predictable, allowable effects which are merely "physical" but do include often flattened affect and memory, emotive and cognitive effects. These drug effects may then be cited capriciously as further evidence to confirm the diagnosis as correct, confusing cause and effect.
When "improvement" is measured in industry research studies, attention is given only to the "main" effect—typically a complex, indirect, interpersonal, perceptual, cultural change, thereby confusing cause with coincidence. There does not exist in chemical imbalance theories, effectiveness measures using standard social networks and associated tests before and after drug administration.
Chemical imbalance theories predominate in "streamline" public sector medicine for lower social class
Social class
Social classes are economic or cultural arrangements of groups in society. Class is an essential object of analysis for sociologists, political scientists, economists, anthropologists and social historians. In the social sciences, social class is often discussed in terms of 'social stratification'...
and homeless persons, where drugs constitute the only form of treatment. There is much wishful thinking in attribution of drug effect, particularly in cases like schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
, where there no longer exists a patient [non-drug user] control group available.
One criticism while not outright rejecting the theory is that it has been scientifically proven that things other than drugs can influence brain chemistry. Exercise releases 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. Even our own thoughts change our brain chemistry. These natural methods of changing brain chemicals are claimed by critics to be preferable to drugs since drugs have side effects. Furthermore, some psychiatric drugs might alter the mind by disabling mood
Mood
Mood may refer to:*Mood , a relatively long lasting emotional state*Grammatical mood, one of a set of morphologically distinctive forms that are used to signal modality*Mood , a city in Iran*Mood District, a district in Iran...
s and emotion
Emotion
Emotion is a complex psychophysiological experience of an individual's state of mind as interacting with biochemical and environmental influences. In humans, emotion fundamentally involves "physiological arousal, expressive behaviors, and conscious experience." Emotion is associated with mood,...
s not just in circumstances where they're a problem but in circumstances where they're appropriate or even beneficial as well while natural ways to change brain chemistry can be used as needed.