DMT has also shown effectiveness in treating addiction. In an observational study of participants treated with the Amazonian folk medicine ayahuasca, a plant-based preparation containing DMT, statistically significant reductions were seen in the use of substances such as alcohol and cocaine after 6 months with no lasting adverse affects.


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Recent studies in Canada, Switzerland, and the United States are investigating the effectiveness of MDMA in treating PTSD. A US study involving 20 participants with an average illness duration of 19 years showed that the treatment “may improve upon the best currently available pharmacotherapies and psychotherapies.”

Significantly more participants treated with MDMA showed a more than 30% reduction in symptom severity compared with placebo (83% in the MDMA group vs 25% in the placebo group). At the end of the study period, some members in the MDMA group no longer met criteria for PTSD according to definitions in the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV).

Data from a recent study conducted in Switzerland also indicated significant reductions in self-reported PTSD symptoms, and in 2015 researchers in Vancouver began a similar pilot study, which is the first Canadian psychedelic drug study initiated in more than 40 years.

Potential Implications

Previous questionable methods employed in the 1950s and 1960s — such as disagreements about the suitability of randomized controlled trials and the possibility of double-blinding, as well as violations of ethical protocols such as lack of informed consent — led to a break in psychedelic drugs research in the 1970s.

However, “recent clinical studies have shown that studies on psychedelics as therapeutic agents can conform to the rigorous scientific, ethical, and safety standards expected of contemporary medical research.” Patients undergo careful screening, and those with potential health risks such as a personal or family history of bipolar disorder or psychosis are eliminated from participation. For those deemed suitable for participation, fully informed consent is obtained, sessions are held in relaxing settings with supervision by a two-person cotherapist team, and protocols are approved by ethics review boards.

The authors of the CMAJ analysis emphasize that as these are small-scale studies further research is necessary. However, policymakers and healthcare professionals should be aware of the potential clinical applications and economic benefits of treating anxiety, depression, addiction, and PTSD with psychedelic therapies.

Laura Stiles is an assistant editor for Psychiatry Advisor.


1. Tupper KW, Wood E, Yensen R, Johnson MW. Psychedelic medicine: a re-emerging therapeutic paradigm. CMAJ. 2015; doi:10.1503/cmaj.141124.