Psychedelics Promising for Anxiety, Depression, Addiction, and PTSD

After several decades of little to no research on the medical benefits of psychedelics, recent small-scale studies in Canada, Europe, and the United States have found some success in using these drugs to treat patients with anxiety, depression, addiction, and post-traumatic stress disorder (PTSD) with few, if any, serious adverse effects, according to an analysis in CMAJ.

“Continued medical research and scientific inquiry into psychedelic drugs may offer new ways to treat mental illness and addiction in patients who do not benefit from currently available treatments,” wrote Evan Wood, MD, PhD, a professor of medicine and at the University of British Columbia, Canada, and colleagues.

Psychedelic drugs “have strong effects on conscious experience” and include substances such as lysergic acid diethylamide (LSD), psilocybin (found in “magic mushrooms”), dimethyltryptamine (DMT), mescaline, and methylenedioxymethamphetamine (MDMA), also known as ecstasy.  

The CMAJ analysis examined several small-scale trials that studied the use of psychedelic drugs to treat anxiety, depression, addiction, and PTSD.

Anxiety and Depression

A small trial conducted in 2014 in Switzerland demonstrated the potential for LSD-assisted psychotherapy to reduce anxiety stemming from terminal illness. At two-month follow-up, participants who were randomly assigned to treatment with LSD showed significant reductions in state anxiety. At one-year follow-up, participants in the LSD group demonstrated sustained therapeutic benefit with no acute or chronic adverse affects.

Findings from a 2008 study also showed that psilocybin may be an effective treatment for anxiety. Patients with end-stage cancer who were given psilocybin-assisted psychotherapy had lowered anxiety and improved mood, also without clinically significant adverse effects.

MDMA is also being evaluated in ongoing studies as treatment for social anxiety in adults with autism.


Interest in the effectiveness of psychedelic agents in treating addiction is being renewed after studies in the 1950s and 1960s showed significant benefits in treating alcohol dependence. In a study conducted in New Mexico, participants treated with psilocybin-assisted therapy self-reported that average percent drinking days and heavy drinking days were reduced by more than half.

Other research has shown benefits in treating tobacco dependence. A pilot study involved 15 participants who smoked at least 10 cigarettes a day and who had several previous failed cessation attempts with cognitive behavioral therapy before and after psilocybin treatment. Six months after the study, 12 of the 15 participants were tobacco-free.