Return of the psychedelics: Psilocybin for treatment resistant depression.

Psilocybin, the clinically most researched classic psychedelic has recently been tested for its safety and efficacy in a clinical population of treatment resistant depression. The efficacy of psilocybin in clinical depression previously demonstrated in the elecrophysiologic and neuroimaging findings as also in neuropsychological assessments is further validated by the findings of this rigorously conducted randomized trial. Mechanism of action of psilocybin and efficacy in treatment resistant depression are discussed in this paper. Ethical issues of conducting clinical trials with psychedelics are also discussed with particular emphasis on their relative safety and absence of addiction potential. Implications of these issues for conduct of larger trials for establishing risk benefit ratio in treatment resistant depression are further suggested.