Abstract
While anecdotal evidence suggests that select 5-hydroxytryptamine 2A (5-HT2A) receptor ligands, including psilocybin, may have long-lasting therapeutic effects after limited dosing in headache disorders, controlled investigations are lacking. In an exploratory double-blind, placebo-controlled, cross-over study, adults with migraine received oral placebo and psilocybin (0.143 mg/kg) in 2 test sessions spaced 2 weeks apart. Subjects maintained headache diaries starting 2 weeks before the first session until 2 weeks after the second session. Physiological and psychological drug effects were monitored during sessions and several follow-up contacts with subjects were carried out to assure safety of study procedures. Ten subjects were included in the final analysis. Over the 2-week period measured after single administration, the reduction in weekly migraine days from baseline was significantly greater after psilocybin (mean, −1.65 (95% CI: −2.53 to −0.77) days/week) than after placebo (−0.15 (−1.13 to 0.83) days/week; p = 0.003, t(9) = 4.11). Changes in migraine frequency in the 2 weeks after psilocybin were not correlated with the intensity of acute psychotropic effects during drug administration. Psilocybin was well-tolerated; there were no unexpected or serious adverse events or withdrawals due to adverse events. This exploratory study suggests there is an enduring therapeutic effect in migraine headache after a single administration of psilocybin. The separation of acute psychotropic effects and lasting therapeutic effects is an important finding, urging further investigation into the mechanism underlying the clinical effects of select 5-HT2A receptor compounds in migraine, as well as other neuropsychiatric conditions.