Objective: An unusual side effect of hallucinogen use is the appearance of hallucinogen persisting perception disorder (HPPD). Despite high rates of prior hallucinogen use among individuals with schizophrenia, there are insufficient data on the clinical characteristics of individuals with co-occurring schizophrenia and HPPD.
Methods: Twenty-six hospitalized patients with schizophrenia and prior LSD use (12 with HPPD and 14 without HPPD) were recruited. Participants were clinically assessed using validated tools, and details regarding hospitalizations were retrieved from their medical records. Those patients who also had HPPD completed a questionnaire addressing HPPD-associated perceptual disturbances.
Results: Participants were mostly male (n = 22, 84.6%) and had an average age of 32.3 (SD = 7.67). Nearly half (n = 12, 46.2%) met criteria for HPPD. No significant differences were found in sociodemographic and clinical characteristics (including response to antipsychotic medications and adverse effects) between the groups. Nine individuals (75%) in the schizophrenia and HPPD group reported the ability to identify specific precursory cues for the appearance of the HPPD-associated perceptual distortions, and 8 (67%) reported the ability to distinguish HPPD perceptual disturbances from those associated with their psychotic disorder.
Conclusions: Very little is known about the co-occurrence of schizophrenia and HPPD or the associated clinical implications. Further research is needed to understand the clinical impact of this comorbidity.
Keywords: HPPD; LSD; co-occurring disorders; flashbacks; hallucinogen persisting perception disorder; schizophrenia.