Hallucinogen persisting perception disorder
Encyclopedia
Hallucinogen persisting perception disorder (HPPD) is a disorder characterized by a continual presence of visual
disturbances that are reminiscent of those generated by the ingestion
of hallucinogenic substances. Previous use of hallucinogens by the person is needed, though not sufficient, for diagnosing someone with the disorder. For an individual to be diagnosed with HPPD, the symptoms cannot be due to another medical condition. HPPD is distinct from flashback
s by reason of its relative permanence; while flashbacks are transient, HPPD is persistent. HPPD is a DSM-IV diagnosis with diagnostic code
292.89.
There are a number of perceptual
changes that can accompany HPPD. Typical symptoms of the disorder include: halo
s or auras surrounding objects, trails following objects in motion, difficulty distinguishing between colors, apparent shifts in the hue
of a given item, the illusion of movement in a static setting, air assuming a grainy or textured quality (visual snow
or static
, by popular description, not to be confused with the normal "blue field entoptic phenomenon
"), distortions in the dimension
s of a perceived object, and a heightened awareness of floater
s. The visual alterations experienced by those with HPPD are not homogeneous and there appear to be individual differences in both the number and intensity of symptoms.
Visual aberrations can occur periodically in healthy individuals – e.g. afterimage
s after staring at a light, noticing floaters inside the eye, or seeing specks of light in a darkened room. However, in people with HPPD, symptoms are typically so severe that the individual cannot ignore them and HPPD is associated with new visual disturbances. It does not appear to merely increase those already in existence.
It also should be noted that the visuals do not constitute true hallucination
s in the clinical sense of the word; people with HPPD recognize the visuals to be illusory, or pseudohallucination
s, and thus demonstrate no inability to determine what is real (in contrast to, e.g., Schizophrenia
).
members who had taken the hallucinogenic cactus peyote
on at least 100 occasions. In a presentation of preliminary results from ongoing research, Matthew Baggott and colleagues from University of California Berkeley found that HPPD-like symptoms occurred in 4.1% of participants (107 of 2,679) in a web-based survey of hallucinogen users. These people reported visual problems after drug use that were serious enough that they considered seeking professional help. This number may over-estimate the prevalence of HPPD since people with visual problems may have been more interested in completing the researchers' questionnaire. The authors reported that 16,192 people viewed the study information but did not complete the questionnaire. If all these people had used hallucinogens without developing visual problems, then the prevalence of serious visual problems in this larger group would be 0.66%. Since these people were not formally diagnosed in person (and may have had visual problems caused by other disorders), this number may provide a reasonable upper limit on the prevalence of HPPD.
It is possible the prevalence of HPPD has been underestimated by authorities because many people with visual problems relating to drug use either do not seek treatment or, when they do seek treatment, do not admit to having used illicit drugs. In the sample of Baggott, only 16 of the 107 people with possible HPPD had sought help and two of these people had been diagnosed with HPPD. Thus, it may be that HPPD occurs more often than is detected by the health care system.
are disrupted.
In some cases, HPPD appears to have a sudden onset after a single drug experience, strongly suggesting the drug played a direct role in triggering symptoms. But in other cases, people report gradual worsening of symptoms with ongoing drug use. Drugs that have been associated with HPPD include LSD
, 2C-E
, 2C-I
, 5-MeO-DIPT
, MDMA, Psilocybin
, Mescaline
, diphenhydramine
, PCP
, Synthetic cannabis, and high doses of dextromethorphan
.
. Of these, the most prominent are anxiety
, panic attack
s, depersonalization disorder
, and depression
. In the sample of Baggott and colleagues, hallucinogen users with persisting and severe visual problems were significantly more likely to report anxiety and depression diagnoses than hallucinogen users without serious visual problems. For example, 25.9% of hallucinogen users with visual problems reported current or past diagnosis of depression. While it is difficult, if not impossible, to establish a clear relationship between the visual and mental symptoms, those with HPPD often testify that a connection indeed exists. For example, anxiety can cause the visuals to become more prominent and vice-versa. Anecdotal wisdom thus maintains that there is a synergistic link between the two. However, there appear to be people with 'pure' cases of HPPD in which no other disorders co-exist.
diazepam (Valium) and alprazolam (Xanax) are prescribed with a fair amount of success. The anticonvulsant drug Levetiracetam has been reported to diminish some of the visual symptoms, as well as reduce depersonalization
and derealization
symptoms , that can occur along with HPPD. Some medications have been contraindicated on the basis of their effects on HPPD or the concurrent mental issues. The atypical antipsychotic
Risperidone is reported to worsen symptoms of HPPD during the drug's duration in some people.
Those with HPPD are often advised to discontinue all drug
use
, many of which are thought to increase visuals in the short-term. There are also less concrete factors that may be generally detrimental to those with HPPD. For example, sleep deprivation
and stress
are thought to increase HPPD symptoms. However, no published studies have investigated whether any of these recommendations are helpful.
There is no universal time course of HPPD recovery. The adverse psychological effects of HPPD (assuming these effects appeared at all) appear to lessen more rapidly than the visuals; quality of life often returns as a person adjusts. Recovery may be facilitated by a psychological habituation to the visuals, which, in effect, reduces the victim’s inclination to attend to and react negatively to them. The deleterious consequences of the visuals can therefore be reduced even if the HPPD does not disappear.
There is currently little reliable information on how often people fully recover from HPPD. There have been reports of HPPD victims having normal perception totally return. The small number of cases of HPPD that have been studied in depth make it difficult to determine how often and under what conditions the visual symptoms of HPPD resolve.
, a teaching affiliate of Harvard Medical School
. David Kozin, consulting with multiple investigators, is involved in designing HPPD-related research.
s (material floating in the eye fluid that appears as black/dark objects floating in front of the eyes and are particularly visible when looking at the bright sky or on a white wall) and the white blood cells of the retinal blood vessels (seen as tiny, fast-moving and quickly disappearing white specks). Likewise, bright lights in an otherwise dark environment may generate trails and halos. Most people don't notice these effects, because they are so used to them. A person fearful of having acquired HPPD may be much more conscious about any visual disturbance, including those that are normal. In addition, visual problems can be caused by brain infections or lesions, epilepsy, and a number of mental disorders (e.g., delirium, dementia, schizophrenia, Parkinson's disease). For an individual to be diagnosed with HPPD, these other potential causes must be ruled out.
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
disturbances that are reminiscent of those generated by the ingestion
Ingestion
Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in the substance through the mouth into the gastrointestinal tract, such as through eating or drinking...
of hallucinogenic substances. Previous use of hallucinogens by the person is needed, though not sufficient, for diagnosing someone with the disorder. For an individual to be diagnosed with HPPD, the symptoms cannot be due to another medical condition. HPPD is distinct from flashback
Flashback (psychological phenomenon)
A flashback, or involuntary recurrent memory, is a psychological phenomenon in which an individual has a sudden, usually powerful, re-experiencing of a past experience or elements of a past experience. These experiences can be happy, sad, exciting, or any other emotion one can consider...
s by reason of its relative permanence; while flashbacks are transient, HPPD is persistent. HPPD is a DSM-IV diagnosis with diagnostic code
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...
292.89.
Symptoms
Perception
Perception is the process of attaining awareness or understanding of the environment by organizing and interpreting sensory information. All perception involves signals in the nervous system, which in turn result from physical stimulation of the sense organs...
changes that can accompany HPPD. Typical symptoms of the disorder include: halo
Halo (optical phenomenon)
A halo from Greek ἅλως; also known as a nimbus, icebow or gloriole) is an optical phenomenon produced by ice crystals creating colored or white arcs and spots in the sky. Many are near the sun or moon but others are elsewhere and even in the opposite part of the sky...
s or auras surrounding objects, trails following objects in motion, difficulty distinguishing between colors, apparent shifts in the hue
Hue
Hue is one of the main properties of a color, defined technically , as "the degree to which a stimulus can be describedas similar to or different from stimuli that are described as red, green, blue, and yellow,"...
of a given item, the illusion of movement in a static setting, air assuming a grainy or textured quality (visual snow
Visual snow
Visual snow is a transitory or persisting visual symptom where people see snow or television-like static in parts or the whole of their visual fields, especially against dark backgrounds...
or static
Static
Static has several meanings:* Static electricity, a net charge of an object** The triboelectric effect, e.g. from shoes rubbing carpet* White noise, a random signal with a flat power spectral density** Noise , a type of radio interference...
, by popular description, not to be confused with the normal "blue field entoptic phenomenon
Blue field entoptic phenomenon
The blue field entoptic phenomenon or Scheerer's phenomenon is the appearance of tiny bright dots moving quickly along squiggly lines in the visual field, especially when looking into bright blue light...
"), distortions in the dimension
Dimension
In physics and mathematics, the dimension of a space or object is informally defined as the minimum number of coordinates needed to specify any point within it. Thus a line has a dimension of one because only one coordinate is needed to specify a point on it...
s of a perceived object, and a heightened awareness of floater
Floater
Floaters are deposits of various size, shape, consistency, refractive index, and motility within the eye's vitreous humour, which is normally transparent. At young age the vitreous is perfectly transparent, but during life imperfections gradually develop. The common type of floater, which is...
s. The visual alterations experienced by those with HPPD are not homogeneous and there appear to be individual differences in both the number and intensity of symptoms.
Afterimage
An afterimage or ghost image or image burn-in is an optical illusion that refers to an image continuing to appear in one's vision after the exposure to the original image has ceased...
s after staring at a light, noticing floaters inside the eye, or seeing specks of light in a darkened room. However, in people with HPPD, symptoms are typically so severe that the individual cannot ignore them and HPPD is associated with new visual disturbances. It does not appear to merely increase those already in existence.
It also should be noted that the visuals do not constitute true hallucination
Hallucination
A hallucination, in the broadest sense of the word, is a perception in the absence of a stimulus. In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid,...
s in the clinical sense of the word; people with HPPD recognize the visuals to be illusory, or pseudohallucination
Pseudohallucination
A pseudohallucination is an involuntary sensory experience vivid enough to be regarded as a hallucination, but recognised by the patient not to be the result of external stimuli. In other words, it is a hallucination that is recognized as a hallucination, as opposed to a "normal" hallucination...
s, and thus demonstrate no inability to determine what is real (in contrast to, e.g., 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...
).
Prevalence of HPPD
The probability of developing HPPD after consuming a hallucinogen is unknown. In their review article, John Halpern and Harrison Pope write that "the data do not permit us to estimate, even crudely, the prevalence of ‘strict’ HPPD." These authors noted that they had not encountered it in their evaluation of 500 Native American ChurchNative American Church
Native American Church, a religious denomination which practices Peyotism or the Peyote religion, originated in the U.S. state of Oklahoma, and is the most widespread indigenous religion among Native Americans in the United States...
members who had taken the hallucinogenic cactus peyote
Peyote
Lophophora williamsii , better known by its common name Peyote , is a small, spineless cactus with psychoactive alkaloids, particularly mescaline.It is native to southwestern Texas and Mexico...
on at least 100 occasions. In a presentation of preliminary results from ongoing research, Matthew Baggott and colleagues from University of California Berkeley found that HPPD-like symptoms occurred in 4.1% of participants (107 of 2,679) in a web-based survey of hallucinogen users. These people reported visual problems after drug use that were serious enough that they considered seeking professional help. This number may over-estimate the prevalence of HPPD since people with visual problems may have been more interested in completing the researchers' questionnaire. The authors reported that 16,192 people viewed the study information but did not complete the questionnaire. If all these people had used hallucinogens without developing visual problems, then the prevalence of serious visual problems in this larger group would be 0.66%. Since these people were not formally diagnosed in person (and may have had visual problems caused by other disorders), this number may provide a reasonable upper limit on the prevalence of HPPD.
It is possible the prevalence of HPPD has been underestimated by authorities because many people with visual problems relating to drug use either do not seek treatment or, when they do seek treatment, do not admit to having used illicit drugs. In the sample of Baggott, only 16 of the 107 people with possible HPPD had sought help and two of these people had been diagnosed with HPPD. Thus, it may be that HPPD occurs more often than is detected by the health care system.
Causes
The cause(s) of HPPD are not yet known. The most current neurological research indicates that HPPD symptoms may manifest from abnormalities in CNS function, following the hallucinogen use. One theory derived from this research is that inhibitory mechanisms involved with sensory gatingSensory gating
Sensory gating describes neurological processes of filtering out redundant or unnecessary stimuli in the brain from all possible environmental stimuli. Also referred to as filtering, or sensorimotor gating, sensory gating prevents an overload of irrelevant information in the higher cortical...
are disrupted.
In some cases, HPPD appears to have a sudden onset after a single drug experience, strongly suggesting the drug played a direct role in triggering symptoms. But in other cases, people report gradual worsening of symptoms with ongoing drug use. Drugs that have been associated with HPPD include 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...
, 2C-E
2C-E
2C-E is a psychedelic and phenethylamine of the 2C family. It was first synthesized by Alexander Shulgin. 2C-E is typically found as a white crystalline powder....
, 2C-I
2C-I
2C-I or 2,5-dimethoxy-4-iodophenethylamine is a psychedelic phenethylamine of the 2C family. It was first synthesized by Alexander Shulgin. It was described in Shulgin’s book PiHKAL: A Chemical Love Story. The drug is used recreationally for its psychedelic and entactogenic effects...
, 5-MeO-DIPT
5-MeO-DIPT
5-methoxy-diisopropyltryptamine is a tryptamine psychedelic used as a recreational drug under the street names "foxy" and "foxy methoxy". 5-MeO-DiPT is orally active, and dosages between 6–20 mg are commonly reported. Many users note an unpleasant body load accompanies higher dosages...
, MDMA, Psilocybin
Psilocybin
Psilocybin is a naturally occurring psychedelic prodrug, with mind-altering effects similar to those of LSD and mescaline, after it is converted to psilocin. The effects can include altered thinking processes, perceptual distortions, an altered sense of time, and spiritual experiences, as well as...
, Mescaline
Mescaline
Mescaline or 3,4,5-trimethoxyphenethylamine is a naturally occurring psychedelic alkaloid of the phenethylamine class used mainly as an entheogen....
, diphenhydramine
Diphenhydramine
Diphenhydramine hydrochloride is a first-generation antihistamine possessing anticholinergic, antitussive, antiemetic, and sedative properties which is mainly used to treat allergies. Like most other first-generation antihistamines, the drug also has a powerful hypnotic effect, and for this reason...
, PCP
Phencyclidine
Phencyclidine , commonly initialized as PCP and known colloquially as angel dust, is a recreational dissociative drug...
, Synthetic cannabis, and high doses of dextromethorphan
Dextromethorphan
Dextromethorphan is an antitussive drug. It is one of the active ingredients in many over-the-counter cold and cough medicines, such as Robitussin, NyQuil, Dimetapp, Vicks, Coricidin, Delsym, and others, including generic labels. Dextromethorphan has also found other uses in medicine, ranging...
.
Co-existing problems
The visual problems of HPPD can occur along with other mental ailmentsMental 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,...
. Of these, the most prominent are anxiety
Anxiety
Anxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...
, panic attack
Panic attack
Panic attacks are periods of intense fear or apprehension that are of sudden onset and of relatively brief duration. Panic attacks usually begin abruptly, reach a peak within 10 minutes, and subside over the next several hours...
s, depersonalization disorder
Depersonalization disorder
Depersonalization disorder is a dissociative disorder in which the sufferer is affected by persistent or recurrent feelings of depersonalization and/or derealization. Diagnostic criteria include persistent or recurrent experiences of feeling detached from one's mental processes or body...
, and depression
Depression (mood)
Depression is a state of low mood and aversion to activity that can affect a person's thoughts, behaviour, feelings and physical well-being. Depressed people may feel sad, anxious, empty, hopeless, helpless, worthless, guilty, irritable, or restless...
. In the sample of Baggott and colleagues, hallucinogen users with persisting and severe visual problems were significantly more likely to report anxiety and depression diagnoses than hallucinogen users without serious visual problems. For example, 25.9% of hallucinogen users with visual problems reported current or past diagnosis of depression. While it is difficult, if not impossible, to establish a clear relationship between the visual and mental symptoms, those with HPPD often testify that a connection indeed exists. For example, anxiety can cause the visuals to become more prominent and vice-versa. Anecdotal wisdom thus maintains that there is a synergistic link between the two. However, there appear to be people with 'pure' cases of HPPD in which no other disorders co-exist.
Treatment
As of yet, there is no cure available for HPPD. The principal treatments seek to reduce symptoms and distress without treating underlying causes. Benzodiazepines including clonazepam (Klonopin),diazepam (Valium) and alprazolam (Xanax) are prescribed with a fair amount of success. The anticonvulsant drug Levetiracetam has been reported to diminish some of the visual symptoms, as well as reduce depersonalization
Depersonalization
Depersonalization is an anomaly of the mechanism by which an individual has self-awareness. It is a feeling of watching oneself act, while having no control over a situation. Sufferers feel they have changed, and the world has become less real, vague, dreamlike, or lacking in significance...
and derealization
Derealization
Derealization is an alteration in the perception or experience of the external world so that it seems unreal. Other symptoms include feeling as though one's environment is lacking in spontaneity, emotional coloring and depth. It is a dissociative symptom of many conditions, such as psychiatric and...
symptoms , that can occur along with HPPD. Some medications have been contraindicated on the basis of their effects on HPPD or the concurrent mental issues. The atypical antipsychotic
Antipsychotic
An antipsychotic is a tranquilizing psychiatric medication primarily used to manage psychosis , particularly in schizophrenia and bipolar disorder. A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s...
Risperidone is reported to worsen symptoms of HPPD during the drug's duration in some people.
Those with HPPD are often advised to discontinue all drug
Drug
A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...
use
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...
, many of which are thought to increase visuals in the short-term. There are also less concrete factors that may be generally detrimental to those with HPPD. For example, sleep deprivation
Sleep deprivation
Sleep deprivation is the condition of not having enough sleep; it can be either chronic or acute. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and weight loss or weight gain. It adversely affects the brain and cognitive function. Few studies have compared the...
and stress
Stress (medicine)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
are thought to increase HPPD symptoms. However, no published studies have investigated whether any of these recommendations are helpful.
There is no universal time course of HPPD recovery. The adverse psychological effects of HPPD (assuming these effects appeared at all) appear to lessen more rapidly than the visuals; quality of life often returns as a person adjusts. Recovery may be facilitated by a psychological habituation to the visuals, which, in effect, reduces the victim’s inclination to attend to and react negatively to them. The deleterious consequences of the visuals can therefore be reduced even if the HPPD does not disappear.
There is currently little reliable information on how often people fully recover from HPPD. There have been reports of HPPD victims having normal perception totally return. The small number of cases of HPPD that have been studied in depth make it difficult to determine how often and under what conditions the visual symptoms of HPPD resolve.
Current Research
A HPPD research program is under development at McLean HospitalMcLean Hospital
McLean Hospital is a psychiatric hospital in Belmont, Massachusetts.It is noted for its clinical staff expertise and ground-breaking neuroscience research...
, a teaching affiliate of Harvard Medical School
Harvard Medical School
Harvard Medical School is the graduate medical school of Harvard University. It is located in the Longwood Medical Area of the Mission Hill neighborhood of Boston, Massachusetts....
. David Kozin, consulting with multiple investigators, is involved in designing HPPD-related research.
Other disorders with similar symptoms
It must be emphasized that individuals without HPPD will sometimes notice visual abnormalities. These include floaterFloater
Floaters are deposits of various size, shape, consistency, refractive index, and motility within the eye's vitreous humour, which is normally transparent. At young age the vitreous is perfectly transparent, but during life imperfections gradually develop. The common type of floater, which is...
s (material floating in the eye fluid that appears as black/dark objects floating in front of the eyes and are particularly visible when looking at the bright sky or on a white wall) and the white blood cells of the retinal blood vessels (seen as tiny, fast-moving and quickly disappearing white specks). Likewise, bright lights in an otherwise dark environment may generate trails and halos. Most people don't notice these effects, because they are so used to them. A person fearful of having acquired HPPD may be much more conscious about any visual disturbance, including those that are normal. In addition, visual problems can be caused by brain infections or lesions, epilepsy, and a number of mental disorders (e.g., delirium, dementia, schizophrenia, Parkinson's disease). For an individual to be diagnosed with HPPD, these other potential causes must be ruled out.
See also
- DepersonalizationDepersonalizationDepersonalization is an anomaly of the mechanism by which an individual has self-awareness. It is a feeling of watching oneself act, while having no control over a situation. Sufferers feel they have changed, and the world has become less real, vague, dreamlike, or lacking in significance...
- Brain FogBrain fogCognitive dysfunction is defined as unusually poor mental function, associated with confusion, forgetfulness and difficulty concentrating...
- NeurocognitiveNeurocognitiveNeurocognitive is a term used to describe cognitive functions closely linked to the function of particular areas, neural pathways, or cortical networks in the brain substrate layers of neurological matrix at the cellular molecular level...
- Thought disorderThought disorderIn psychiatry, thought disorder or formal thought disorder is a term used to describe incomprehensible language, either speech or writing, that is presumed to reflect thinking. There are different types...
- Effects of MDMA on the human bodyEffects of MDMA on the human bodyThe effects of MDMA on the human brain and body are complex, interacting with several neurochemical systems. It induces serotonin, dopamine, and norepinephrine release, and can act directly on a number of receptors, including α2-adrenergic and 5HT2A receptors...