High-Concentration Delta-9-Tetrahydrocannabinol Cannabis Products and Mental Health Outcomes : A Systematic Review.
Annals of internal medicine October 1, 2025 Thanitsara Rittiphairoj, Louis Leslie, Jean-Pierre Oberste et al. 12 citations
High-concentration THC cannabis products are consistently linked to worse mental health outcomes, especially psychosis or schizophrenia and cannabis use disorder. Among 99 studies (over 221,000 participants), 70% of non-therapeutic studies found unfavorable associations with psychosis or schizophrenia, and 75% found unfavorable associations with cannabis use disorder. For anxiety and depression, about half of non-therapeutic studies reported unfavorable associations, particularly in healthy populations. Some therapeutic studies suggested benefits for anxiety (47%) and depression (48%), but these findings were low-quality and inconsistent. More than 95% of the studies had moderate or high risk of bias.