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Hallucinogen persisting perception disorder: what do we know after 50 years?
John H Halpern1, Harrison G Pope
1Harvard Medical School, Biological Psychiatry Laboratory, Alcohol and Drug Abuse Research Center, McLean Hospital, 115 Mill Street, Belmont, MA 02478-9106, USA. john_halpern@hms.harvard.edu
Drug and Alcohol Dependence
|March 1, 2003
Summary
Hallucinogen Persisting Perception Disorder (HPPD), or flashbacks, is a rare but genuine condition following hallucinogen use. Current knowledge is limited, with inconsistent definitions and insufficient data on risk factors and treatments.
Area of Science:
- Psychiatry
- Neuroscience
- Pharmacology
Background:
- Hallucinogen Persisting Perception Disorder (HPPD), commonly known as flashbacks, has been recognized for decades.
- The phenomenon is documented in diagnostic manuals like DSM-IV, but historical studies often lack current diagnostic criteria.
- Existing research presents challenges in interpretation due to varying definitions and methodologies.
Purpose of the Study:
- To review and analyze quantitative studies on HPPD published between 1955 and 2001.
- To assess the current state of knowledge regarding HPPD's prevalence, etiology, and treatment.
- To identify limitations in existing research and highlight areas for future investigation.
Main Methods:
- Systematic literature search for quantitative studies on HPPD.
- Analysis of 20 studies published from 1955 to 2001.
- Evaluation of study methodologies against current diagnostic criteria (DSM-III-R, DSM-IV).
Main Results:
- Current understanding of HPPD is significantly limited due to inconsistent terminology and insufficient data.
- Most studies predate formal diagnostic criteria, making it difficult to ascertain HPPD prevalence or meet current diagnostic standards.
- HPPD is an uncommon but genuine disorder, often associated with illicit LSD use, causing significant morbidity.
Conclusions:
- The term 'flashbacks' lacks a consistent definition, hindering research.
- There is a critical need for further research to establish prevalence, understand etiologic mechanisms, and develop evidence-based treatments for HPPD.
- While case reports suggest potential treatments (e.g., neuroleptics, anticonvulsants), randomized controlled trials are lacking.