19 May Karolinska Institutet Evaluates Single Dose of Psilocybin for Depression
Editor’s note: This piece discusses mental health issues. If you have experienced suicidal thoughts or have lost someone to suicide and want to seek help, you can contact the Crisis Text Line by texting “START” to 741-741 or call the Suicide Prevention Lifeline at 800-273-8255.
Dr. Hampus Yngwe
MedicalResearch.com Interview with:
Hampus Yngwe, MD, MSc
Centre for Psychiatry Research,
Department of Clinical Neuroscience,
Karolinska Institutet, and
Stockholm Health Care Services
Stockholm, Sweden
MedicalResearch.com: What is the background for this study?
Response: Depression is a common and disabling condition and current treatments do not work for all patients. Psilocybin has shown promise as a rapid-acting treatment, but more controlled studies are needed to clarify its effects, durability and safety.
MedicalResearch.com: What are the main findings?
Response: In our randomized, double-blind trial, a single dose of psilocybin given with psychological support led to a rapid reduction in depressive symptoms compared with the active placebo Niacin. The effect was evident at day 8 and remained present for more than three months during follow-up in self-reports.
MedicalResearch.com: Is there a recommended protocol for administering or following up on treatment with psilocybin?
Response: In the trial, psilocybin was administered according to a structured set-and-setting protocol for safety reasons. This included careful screening and five treatment sessions: preparation before dosing, a supervised dosing session with trained psychologists, and three integration sessions afterwards.
MedicalResearch.com: What should readers take away from your report?
Response: Our study shows a rapid antidepressant effect at day 8, but also a sustained effect over more than three months compared with the control group. The treatment also appeared feasible to administer safely within a structured clinical trial setting, although some participants may require extra support due to anxiety. If these results hold up in larger studies, psilocybin could become clinically useful as a complement to existing treatments for depression.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: Future studies should be larger and include longer follow-up, careful assessment of blinding and expectancy effects, safety monitoring, and evaluation of which patients are most likely to benefit, as well as pragmatic comparisons of psilocybin to routine care.
MedicalResearch.com: Is there anything else you would like to add? Any disclosures?
Response: Psilocybin remains a controlled substance and should not be used outside appropriate clinical or regulatory settings. Our research group is currently investigating whether psilocybin affects synaptic density using PET imaging and results will be published later.
Citation:
Yngwe H, Plavén-Sigray P, Ekman CJ, et al. Short-Term and Late-Term Effects of Psilocybin on Symptoms in Major Depression: A Randomized Clinical Trial. JAMA Netw Open. 2026;9(5):e2612589. doi:10.1001/jamanetworkopen.2026.12589
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Last Updated on May 19, 2026 by Marie Benz MD FAAD