Classic Psychedelics in Translational Research: Addressing Epistemic Challenges from Bench to Bedside

In the last decade alone, a growing body of preliminary evidence suggests that classic psychedelics (CPs) can rapidly and durably ameliorate symptoms and cognitive deficits associated with depression. However, the mechanisms by which CPs work in the brain are not well understood. Rodent translational research, in which experimental findings from rodents are translated to humans, is fundamental in achieving this goal. This chapter focuses on a representative subset of human and rodent studies investigating CPs for depression, including the various lines of research that have been initiated to understand how they work. Our aim is to show that in addition to epistemic challenges that scientists face in translating findings from rodents to humans, there is also mismatch between experimental approaches used to investigate CPs in humans and rodents. We thus show current experimental practices are not conducive to mechanistic discovery. We end with a set of positive proposals to expedite the drive to translate CPs into effective treatments for depression. Keywords: classic psychedelics, psychiatry, clinical trials, collaboration, extrapolation, major depressive disorder, open science, philosophy of science, rodent models, scientific practice, translation, validity