Hallucinogen persisting perception disorder
|Hallucinogen persisting perception disorder|
|HPPD noise simulation, often referred to as visual snow|
Hallucinogen persisting perception disorder (HPPD) is a disorder in which a person has flashbacks of visual hallucinations or distortions experienced during a previous hallucinogenic drug experience, sometimes with the same feelings experienced before, which cause distress or impairment in work or everyday life. The flashbacks may be continuous or just occasional.
The only certain cause for HPPD is prior use of hallucinogens. There are no known risk factors, and what might trigger any specific disturbing hallucination is not known. Some sort of disinhibition of visual processing may be involved.
As of 2018 there was no good evidence for any treatment. For people diagnosed with chronic HPPD, sunglasses and therapy might help. Antipsychotic drugs and SSRIs have been reported to help some people and worsen symptoms for others. Anticonvulsants and clonidine have also been tried.
The prevalence of HPPD was unknown as of 2018. Estimates in the 1960s and 1970s were around 1 in 20 for intermittent HPPD among regular users of hallucinogens. It is not clear if chronic HPPD exists, but one estimate in the 1990s was that 1 in 50,000 regular users might have chronic disturbing hallucinations.
- Halpern, JH; Lerner, AG; Passie, T (2018). “A Review of Hallucinogen Persisting Perception Disorder (HPPD) and an Exploratory Study of Subjects Claiming Symptoms of HPPD”. Current topics in behavioral neurosciences. 36: 333–360. doi:10.1007/7854_2016_457. PMID 27822679.
- G Lerner, A; Rudinski, D; Bor, O; Goodman, C (2014). “Flashbacks and HPPD: A Clinical-oriented Concise Review”. The Israel journal of psychiatry and related sciences. 51 (4): 296–301. PMID 25841228.