A randomized placebo-controlled trial tested three concentrations of smoked cannabis (high THC, high CBD, THC+CBD) against placebo in military veterans with PTSD. Over three weeks, all groups including placebo showed significant improvements in PTSD symptom severity, but none of the active cannabis concentrations outperformed placebo statistically. The treatments were generally well tolerated. This preliminary trial did not find evidence that smoked cannabis is more effective than placebo for PTSD symptoms in the short term, highlighting the need for further well-powered studies.
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.