DSM-IV

In DSM-IV, this disorder is called Hallucinogen Persisting Perception Disorder (Flashbacks)

The essential feature of Hallucinogen Persisting Perception Disorder (Flashbacks) is the transient recurrence of disturbances in perception that are reminiscent of those experiences during one or more earlier Hallucinogen Intoxications. The person must have had no recent Hallucinogen Intoxication and must show no current drug toxicity (Criterion A). This reexperiencing of perceptual symptoms causes clinically significant distress or impairment in social, occupational, or other important areas of functioning (Criterion B). The symptoms are not due to a general medical condition (e.g., anatomical lesions and infections of the brain or visual epilepsies) and are not better accounted for by another mental disorder (e.g., delirium, dementia, or Schizophrenia) or by hypnopompic hallucinations (Criterion C). The perceptual disturbances may include geometric forms, peripheral-field images, flashes of color, intensified colors, trailing images (images left suspended in the path of a moving object as seen in stroboscopic photography), perceptions of entire objects, afterimages (a same-colored or complementary colored "shadow" of an object remaining after removal of the object), halos around objects, macropsia, and micropsia. The abnormal perceptions that are associated with Hallucinogen Persisting Perception Disorder occur episodically and may be self-induced (e.g., by thinking about them) or triggered by entry into a dark environment, various drugs, anxiety or fatigue, or other stressors. The episodes may abate after several months, but may persons report persisting episodes for 5 years or longer. Reality testing remains intact (i.e., the person recognizes that the perception is a drug effect and does not represent external reality). In contrast, if the person has a delusional interpretation concerning the etiology of the perceptual disturbance, the appropriate diagnosis would be Psychotic Disorder Not Otherwise Specified.

Diagnostic Criteria

A. The reexperiencing, following cessation of use of a hallucinogen, of one or more of the perceptual symptoms that were experiences while intoxicated with the hallucinogen (e.g., geometric hallucinations, false perceptions of movement in the peripheral visual fields, flashes of color, intensified colors, trails of images of moving objects, positive afterimages, halos around objects, macropsia, and micropsia).

B. The symptoms in Criterion A cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.

C. The symptoms are not due to a general medical condition (e.g., anatomical lesions and infections of the brain, visual epilepsies) and are not better accounted for by another mental disorder (e.g., delirium, dementia, Schizophrenia) or hypnopompic hallucinations.

DSM-5

Diagnostic Criteria

A. Following cessation of use of a hallucinogen, the reexperiencing of one or more of the perceptual symptoms that were experienced while intoxicated with the hallucinogen (e.g., geometric hallucinations, false perceptions of movement in the peripheral visual fields, flashes of color, intensified colors, trails of images of moving objects, positive afterimages, halos around objects, macropsia and micropsia).

B. The symptoms in Criterion A cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.

C. The symptoms are not attributable to another medical condition (e.g., anatomical lesions and infections of the brain, visual epilepsies) and are not better explained by another mental disorder (e.g., delirium, major neurocognitive disorder, schizophrenia) or hypnopompic hallucinations.

Differential Diagnosis

Conditions to be ruled out include schizophrenia, other drug effects, neurodegenerative disorders, stroke, brain tumors, infections, and head trauma. Neuroimaging results in hallucinogen persisting perception disorder cases are typically negative. Reality testing remains intact (i.e., the individual is aware that the disturbance is linked to the effect of the drug); if this is not the case, another disorder (e.g., a psychotic disorder, another medical condition) might better explain the abnormal perceptions.

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