Hallucinogen persisting perception disorder

Hallucinogen persisting perception disorder, usually abbreviated HPPD, is a non-psychotic condition in which a person continues to experience lasting or recurring visual hallucinations or perceptual distortions well after they have used a drug such as a psychedelic, a dissociative, a deliriant, an entactogen or a cannabinoid. The visual symptoms reported include visual snow, trailing images and afterimages known as palinopsia, geometric fractal patterns seen on flat surfaces, intensified colors, altered perception of motion, pareidolia, and objects appearing smaller or larger than they are. Diagnosis requires clinicians to rule out other psychological, psychiatric and neurological explanations for the symptoms, and the disturbance must cause measurable distress or impairment in daily life; the DSM-5 catalogues the condition under code 292.89, also written F16.983. The disorder is generally divided into two recognized types: type one involves brief, sporadic flashback-like episodes that can resolve over months or years, while type two describes a chronic and more severe form that tends to persist for life. HPPD is considered distinct from a hallucinogen-induced psychotic disorder because it does not involve paranoia, insomnia, disordered thinking or delusions, and centers instead specifically on persistent visual disturbance.