Most Evidence Suggests Medical Cannabis Has Minor Effects on Thinking Skills

Of 23 included studies (917 total participants), 15 found non-significant effects on cognition, 6 found impairments, 1 found improvement, and 1 found improvement after withdrawal. In studies that did find significant impairment, test scores remained within normal ranges or below clinical impairment thresholds.

Systematic review searching EMBASE, PsycINFO, PubMed, and Scopus. Included studies had to use cannabis-based medicines in controlled settings, measure cognition with recognized tests, and use within-subjects designs. Excluded studies on abuse, abstinence, severe neurodegeneration, and cancer pain. Two independent researchers conducted screening and risk of bias assessment.

Cognitive side effects are a common concern for patients considering medical cannabis. This review provides reassurance that at therapeutic doses, cognitive impairment appears minor, while also flagging that long-term use remains an open question.

As medical cannabis prescriptions grow worldwide, understanding cognitive trade-offs is essential for informed treatment decisions. This review suggests the cognitive cost may be lower than many patients and clinicians fear, at least in the short term.

Large heterogeneity across studies in terms of cannabis products, doses, cognitive measures, and patient populations. Most studies used relatively low THC doses. Limited evidence on long-term cognitive effects of medical cannabis use.