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Psilocybin-Assisted Therapy Showing Promise, but More Research Needed

October 05, 2019

SAN DIEGO—Psilocybin-assisted psychotherapy is showing promise in research examining effects on depressive symptoms and substance use, but no trials have reached phase 3 and eventual approval of the treatment remains uncertain, a researcher reported at Psych Congress 2019.

Psilocybin-assisted therapy therefore is not as far along in the research pipeline as MDMA-assisted psychotherapy, for which a phase 3 trial for post-traumatic stress disorder is under way, said Josh Woolley, MD, PhD, director of the Bonding and Attunement in Neuropsychiatric Disorders Lab at the University of California, San Francisco's Department of Psychiatry. What is known from mostly open-label studies so far, however, is that one dose of psilocybin appears to have profound and often lasting beneficial effects on mood, Dr. Woolley said.

A pair of phase 2b studies of psilocybin-assisted psychotherapy have been launched, marking the greatest progress so far for this potential treatment option, Dr. Woolley reported. Other current research includes a University of Alabama-Birmingham study of psilocybin-assisted therapy for cocaine dependence.

More from Psych Congress: Momentum Grows for Psychedelics as Part of Mainstream Therapy

Woolley's session summarized a number of studies of psilocybin administration, some using healthy subjects and others examining the effects of a single dose in psilocybin-assisted psychotherapy. The psychedelic, which is believed to produce its psychological effects via binding to 5-HT2A receptors, generates greater arousal and feelings of well-being during treatment in healthy subjects, with positive effects on mood over the long term. Many subjects have characterized the experience of receiving psilocybin in this controlled setting as being among the top 5 experiences of their life, Dr. Woolley said.

Other studies have shown that one session of psilocybin-assisted psychotherapy led to improvements in depressive and anxiety symptoms in patients with a life-threatening cancer diagnosis. The experience appears to help patients get in touch with previously overpowering emotions around illness and mortality. Dr. Woolley pointed out, however, that these findings are limited by relatively small sample sizes and an open-label design.

He also detailed results of a yet-unpublished study conducted at his lab, which used an uncommon design of exploring psilocybin-assisted group therapy rather than individual therapy. The target population in this study was long-term survivors of an AIDS diagnosis in San Francisco, most of whom had lost numerous friends during the height of the epidemic.

The 18-patient study divided participants into three groups of six, with pre-dosing preparation and post-treatment integration sessions occurring in the group and the single-dose treatment session administered individually. Dr. Woolley said that beneficial effects on the primary outcome of demoralization (akin to loss of meaning in life) were apparent within 2 weeks of the treatment and generally persisted at 3-month follow-up.

“Everyone in the study said the experience was beneficial to their mental health,” he said.

Dr. Woolley pointed out some practical considerations if psilocybin-assisted psychotherapy eventually becomes an approved treatment for depression. Since antidepressants blunt the effects of the psilocybin-induced experience, patients would have to taper off any antidepressant treatment before initiating the therapy, he said.

—Gary Enos


“Psilocybin-assisted psychotherapy for psychiatric illness: research update.” Presented at Psych Congress 2019: San Diego, CA; October 5, 2019.

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