29/05/2026
A landmark systematic review and meta-analysis published in The Lancet Psychiatry has challenged a rapidly growing sector of modern medicine.
Led by Dr. Jack Wilson at the University of Sydney’s Matilda Centre, the research found no high-quality clinical evidence indicating that medicinal cannabis effectively treats anxiety, depression, or post-traumatic stress disorder (PTSD)—the primary psychiatric conditions for which it is routinely prescribed.
Evaluating 54 randomized controlled trials spanning 45 years of clinical data, the comprehensive study revealed that cannabinoids, including both cannabidiol (CBD) and tetrahydrocannabinol (THC) formulations, failed to outperform placebos in reducing core psychological symptoms.
While medicinal cannabis sales and prescription approvals have tripled over the past four years, the findings expose a stark divergence between public perception and rigorous scientific reality, suggesting that the popular narrative of cannabis as a mental health "cure-all" is largely unsupported by data.
Beyond the lack of proven psychiatric efficacy, researchers raised concerns regarding potential secondary clinical risks.
Although the acute data showed cannabis to be relatively safe over short periods, long-term or chronic use—particularly of high-THC products—carries a well-documented risk of worsening baseline mental health outcomes.
This includes an elevated probability of developing cannabis use disorder (dependency), inducing psychotic symptoms in vulnerable populations, and critically delaying patient access to proven, first-line evidence-based interventions like cognitive behavioral therapy (CBT).
