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Psilocybin may be safe, effective for treatment-resistant depression

Psilocybin may be safe and effective for treatment-resistant depression, according to recent findings.

“Psilocybin is a serotonin receptor agonist that occurs naturally in some mushroom species,” Robin L Carhart-Harris, PhD, of Imperial College London, and colleagues wrote. “Recent studies have assessed the therapeutic potential of psilocybin for various conditions, including end-of-life anxiety, obsessive-compulsive disorder, and smoking and alcohol dependence, with promising preliminary results.”

To determine feasibility, safety and efficacy of psilocybin for unipolar treatment-resistant depression, researchers conducted an open-label feasibility trial among 12 individuals with moderate-to-severe treatment-resistant major depression. Participants received two oral doses of psilocybin — 10 mg and 25 mg, 7 days apart — in a supportive setting and psychological support before, during and after each session. Depressive symptoms were assessed from 1 week to 3 months after treatment.

Researchers found that psilocybin’s psychedelic effects became detectable 30 to 60 minutes after dosing, peaked 2 to 3 hours after dosing and subsided to negligible levels at least 6 hours after dosing.

Mean self-rated intensity, on a 0 to 1 scale, was 0.51 for the low-dose session and 0.75 for the high-dose session.

Psilocybin was well-tolerated, as no serious adverse events occurred, according to researchers.

Adverse reactions included transient anxiety (n = 12), transient confusion or thought disorder (n = 9), mild and transient nausea (n = 4) and transient headache (n = 4).

Depressive symptoms, measured by Quick Inventory of Depressive Symptoms scores, improved 1 week (mean score difference = –11.8; 95% CI, –9.15 to –14; P = .002) and 3 months (mean score difference = –9.2; 95% CI, –5.69 to – 12.71; P = .003) after high-dose treatment, compared with baseline.

Researchers also noted clear and sustained improvements in anxiety and anhedonia.

“Our findings support the feasibility of this approach and the magnitude and duration of the post-treatment reductions in symptom severity motivate further controlled research,” the researchers wrote. “Psilocybin has a novel pharmacological action in comparison with currently available treatments for depression (ie, 5-HT_2A receptor agonism) and thus could constitute a useful addition to available therapies for the treatment of depression.” – by Amanda Oldt

Disclosure: Carhart-Harris reports no relevant financial disclosures. Please see the full study for a list of all authors’ relevant financial disclosures.