Is MDD the right target for early-stage psychedelic-assisted therapy trials?

Abstract

The recently published Imperial College study of a Phase II, double-blind, randomized, controlled trial comparing psilocybin-assisted therapy to a six-week titration of escitalopram for Major Depressive Disorder (MDD) should raise concerns for this illness category as a target of early psychedelic research given a goal of FDA approval. There are three reasons why MDD is the wrong target at this stage of research development. Firstly, the psychiatric category of MDD is heterogeneous, vaguely-defined, and overdiagnosed in a way that will problematize finding a reliable signal with psychedelic interventions (or any intervention), particularly within non-severe cases. Secondly, current rating scales for MDD (QIDS used in the Imperial College trial, but also HAM-D) are limited in approximating the kinds of things we ultimately care most about with depressive states, namely functional status, quality of life, and well-being: measures that seem more salient for psychedelic interventions and which are not adequately captured by these rating scales used in a majority of clinical trials. And thirdly, there are inherent conflicts between psychiatric conceptualizations of MDD (and its symptom amelioration) and the kinds of perspectives on one’s suffering often occasioned by psychedelic experiences themselves: while these kinds of psychedelic-catalyzed openings may lead to a form of acceptance or equanimity with regards to one’s life circumstances this could be in many ways orthogonal to reductions in HAM-D scores. We argue that for these reasons MDD is a non-ideal target at this stage of the science and propose alternative directions.