, a small, nonrandomized clinical trial shows. However, the investigators and other outside experts warn these results should not be overinterpreted.
Three weeks after receiving psilocybin and psychotherapy, all 15 participants’ depression scores dropped by an average of 24 points. Twelve met criteria for response and 11 for remission.
This benefit lasted until the 12-week mark, with 12 participants (80%) meeting criteria for both response and remission. There were no reports of mixed or manic symptoms, psychotic symptoms, or suicidal ideation.
Given the study’s small, open-label design, the findings should be interpreted cautiously, but the investigators say the results are promising.
“The results we saw from this trial are encouraging and further support the clinical study of psychedelics in patients with treatment-resistant bipolar II,” lead investigator Scott T. Aaronson, MD, chief science officer of the Institute for Advanced Diagnostics and Therapeutics at Sheppard Pratt Health System in Baltimore, Maryland, remarked in a press release. “One participant compared the transformation she experienced to taking a deep breath after breathing through a straw for years.”
The findings were published online on December 6, 2023, in JAMA Psychiatry.
Underserved Population
Previous studies show that psilocybin is effective in reducing the symptoms of treatment-resistant depression, major depressive disorder, and anorexia nervosa, most with only mild to moderate adverse effects.
Individuals with bipolar disorder (BPD) have been excluded from psilocybin studies in the last two decades. Investigators attribute this to anecdotal evidence that psychedelics may result in manic episodes in patients with BPD, even though empirical evidence of those effects is limited.
This study included 15 participants (9 female; mean age, 37.8 years) with BDII who had experienced an episode for more than 3 months and failed at least two medications within the current episode.
Participants stopped all psychotropic medications at least 2 weeks prior to the trial and received 25 mg of synthetic COMP360 psilocybin in a controlled setting. Psychotherapy included three sessions before dosing, one during the 8-hour dosing day, and three integration sessions posttreatment.
Depression was measured with the Montgomery Ǻsberg Depression Rating Scale (MADRS) at six points during the 12-week study.
By week 3, all 15 participants had lower MADRS scores, with a mean decrease of 24 points (P < .001). Twelve participants met the response criteria of ≥ 50% reduction in MADRS scores, and 11 met the criteria for remission of a MADRS score of ≤ 10 (both P < .001).
MADRS scores at each posttreatment time point were significantly lower than they were at baseline and the improvement persisted at 12 weeks.
Participants were also monitored for mania and suicidality at various time points during the study, and no significant changes were found from baseline.
“As a first open-label foray into this underserved and treatment-resistant population, care should be taken not to overinterpret the findings,” the authors note, adding that the findings may not apply to patients with BDI or BDII in a mixed or hypomanic phase of their illness.
No Definitive Conclusion
In an accompanying editorial, David B. Yaden, PhD, Johns Hopkins University School of Medicine, Baltimore, Maryland, and colleagues write that the findings are “tantalizingly suggestive,” but ultimately say nothing definitive about the efficacy of psilocybin for BDII.
“The danger is that some individuals will see the large (yet uncontrolled) effect size and believe that a new treatment of bipolar II has been discovered that is substantially better than all other treatments, while neglecting to mention the lack of control condition and substantial psychosocial support included in the study,” Dr. Yaden and colleagues wrote.
They also cautioned that due to the study’s limitations, which include its small sample size and lack of a control group, “it is imperative that the large effect size before to after the study is not overinterpreted.”
However, Dr. Yaden and colleagues also characterized the safety data as “compelling,” noting the safety profile could affect exclusion criteria in future studies involving people with BPD.
“The results of the present study provide preliminary evidence that perhaps those with bipolar II can be safely included in study samples without undue risk of triggering hypomanic episodes,” they wrote. “It also suggests re-evaluation of the need to exclude individuals with mere family history of bipolar II, which several studies do.”
The study was funded by COMPASS Pathways, who provided the study drug. Dr. Aaronson reported grants and nonfinancial support (supply of drug) from COMPASS Pathways during the conduct of the study and personal fees from LivaNova, Neuronetics, Genomind, and Sage Therapeutics outside the submitted work. Other disclosures are noted in the original article.
A version of this article appeared on Medscape.com.