A single dose of the psychedelic psilocybin combined with psychotherapy appears to be safe and effective at reducing depression in people with treatment-resistant bipolar disorder II, according to a small study published today in JAMA Psychiatry. Bipolar II disorder is associated with difficult-to-treat depressive episodes but less severe manic episodes than those experienced by patients with bipolar I disorder.
“The findings support further study of psychedelics in the [bipolar II disorder] population,” wrote Scott Aaronson, M.D., of the Institute for Advanced Diagnostics and Treatment at Sheppard Pratt Health System and colleagues. “Individuals in this study displayed strong and persistent antidepressant effects, with no signal of worsening mood instability or increased suicidality.”
The open-label study included 15 patients (nine female, average age 37.8) with bipolar II disorder who had been experiencing an episode of depression lasting longer than three months. After withdrawal of antidepressants and mood-stabilizing medications for at least two weeks, all study participants received a single 25 mg dose of synthetic psilocybin. Therapists met with the patients for three sessions during pretreatment, during the 8-hour dosing day, and for three integration sessions posttreatment.
A study psychiatrist assessed the participants using the Montgomery-Åsberg Depression Rating Scale (MADRS), the Columbia Suicide Severity Rating Scale (CSSRS), and the Young Mania Rating Scale (YMRS) during follow-up visits at 1, 2, 3, 6, and 12 weeks.
The primary outcome measure for the study was a change in the Montgomery-Åsberg Depression Rating scale (MADRS) at three weeks posttreatment.
At week 3, all 15 patients had lower scores on the MADRS than at baseline (average reduction, 24 points). Twelve participants met the criteria for response (50% decrease in MADRS), and 11 met criterion for remission (MADRS score ≤10). At 12 weeks, 12 patients met both response and remission criteria. There were no significant adverse events related to the psilocybin dosing, and there was no significant change in scores on the safety measures for suicide or mania.
“The results of this trial are relevant for both efficacy and safety. However, the evidence for safety is far more compelling,” wrote David B. Yaden, Ph.D., of the Center for Psychedelic and Consciousness Research at Johns Hopkins University School of Medicine and colleagues in an accompanying editorial.
While the authors acknowledged the limitations of the small study, they noted that “[t]he favorable safety profile of this study strongly justifies a larger randomized clinical trial of psilocybin for bipolar II depression,” they wrote. “Bipolar disorders are associated with substantial suffering and dysfunction, and new treatments are needed.”
For related information, see the Psychiatric News article “Depression Improves Following Single Dose of Psilocybin.”
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