People who have used psychedelics such as psilocybin, LSD, or ayahuasca a mild to moderate number of times over their lives show broadly equivalent neuropsychological performance to non-users, but with a modest advantage in executive functions, particularly cognitive flexibility as measured by the Wisconsin Card Sorting Test (WCST). In matched-pair analyses, users performed better on the WCST, and dose-response analyses within the user group found that greater lifetime use was positively associated with fewer total errors, perseverative responses, perseverative errors, non-perseverative errors, and more conceptual level responses. The study did not find any negative associations between sporadic psychedelic use and cognition.
Psychedelics are being studied as potential treatments for psychological disorders, but their recreational use is also increasing. This chapter reviews the acute, subacute, and long-term neuropsychological effects of psychedelics. Under the influence, attention and working memory are reduced, which can be risky in high-risk environments like driving. These impairments typically resolve the next day, though some executive functioning deficits may persist up to 24 hours. Repeated use does not appear to cause lasting neuropsychological harm, but more research is needed on different substances and chronic use patterns.