Research published in the Lancet Psychiatry and a companion JAMA paper show no evidence that marijuana effectively treats anxiety, depression, or post-traumatic stress disorder—three of the most common reasons cannabis is prescribed. A systematic review analyzed 54 randomized controlled trials published between 1980 and 2025, the gold-standard design for medical research. The cannabis medications in these studies were largely oral formulations including capsules, sprays, and oils; however, people in real-world settings typically use smoked cannabis, which has even less evidence of mental health benefit. Marijuana also failed to improve anorexia nervosa, bipolar disorder, obsessive-compulsive disorder, or psychotic disorders such as schizophrenia.
Despite this lack of evidence, almost every state in the United States approves medical marijuana for mental health conditions. Among 27% of people between ages 16 and 65 in the United States and Canada who have used marijuana for medical purposes, about half report using it to manage mental health. Doctors continue to prescribe medical marijuana for mental health conditions despite the absence of proof of efficacy, a pattern complicated by cannabis industry connections to some studies, creating potential conflicts of interest.
Regular use of potent marijuana poses significant risks, particularly for vulnerable populations. Use during pregnancy, adolescence, and young adulthood interferes with brain development. Heavy use by teens and young adults with mood disorders correlates with increased risk of self-harm, suicide attempts, and death. For individuals at high risk of bipolar or psychotic disorders, marijuana use raises the risk of developing these conditions. Daily users of high-potency cannabis may be six times more likely to develop psychotic disorder compared to non-users.
Modern marijuana is substantially more potent than historical levels, with THC content rising from approximately 4% in the 1970s to an average of 18% to 20% today. Dispensaries now sell products with 35% THC content, and concentrates reach 80%—about 20 times greater than levels from the 1960s and 1970s. This potency increase contributes to rising addiction: approximately 3 in 10 people who use marijuana develop cannabis use disorder. Proven alternatives include selective serotonin reuptake inhibitors (SSRIs) for depression and anxiety, often combined with cognitive behavioral therapy (CBT), a goal-oriented approach addressing negative thoughts and behaviors.
This article is an AI-assisted summary. All facts and figures are drawn from the original report: https://www.cnn.com/2026/03/16/health/marijuana-mental-health-wellness