Unfavorable Mental Health Outcomes Reported With THC Product Use

TUESDAY, Aug. 26, 2025 (HealthDay News) — High-concentration delta-9-tetrahydrocannabinol (THC) cannabis products are associated with unfavorable mental health outcomes, according to a review published online Aug. 26 in the Annals of Internal Medicine.

Thanitsara Rittiphairoj, M.D., M.P.H., from the Johns Hopkins Bloomberg School of Public Health in Baltimore, and colleagues systematically reviewed associations of high-concentration THC cannabis products with mental health outcomes. Ninety-nine studies were included (42, 47, and 11 percent randomized trials, observational studies, and other interventional studies, respectively), with 221,097 participants; more than 95 percent had a moderate or high risk for bias.

The researchers found that high-concentration THC products showed consistent unfavorable associations with psychosis or schizophrenia (70 percent) and cannabis use disorder (CUD; 75 percent) in studies not testing for therapeutic effects. For psychosis and schizophrenia, no therapeutic studies reported favorable results. Overall, 53 and 41 percent of nontherapeutic studies reported unfavorable associations for anxiety and depression, respectively, especially among healthy populations. Nearly half of the therapeutic studies revealed benefits for anxiety and depression (47 and 48 percent, respectively), although unfavorable associations were also seen (24 and 30 percent, respectively).

“The findings with regard to anxiety, depression, psychosis or schizophrenia, and CUD are concerning — even among otherwise healthy persons, potentially including those using the products for recreational purposes — albeit not definitive for causation and imply a need for precautionary guidance,” the authors write.

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