One hundred twenty healthy participants, ages 21 to 70, who experience moderate-to-lower-than-average mental well-being will be evenly randomized into four different study arms, using a 2x2 factorial design. Depending on the study arm, participants will either receive an inactive placebo or up to 25mg psilocybin (oral dose), in one of two set and setting conditions; drug administration contexts that are predicted to modulate drug effects.
The purpose of this study is to evaluate any interaction effects between an oral dose of psilocybin and the surrounding context (set and setting).
2 x 2 Factorial, Double-blind, Randomized Trial of 'Set and Setting': a Translational Study in Healthy Volunteers
Recent research posits that psychedelic medicine is best employed as a combination treatment, i.e., as drug x psychological support or psychotherapy referred to for simplicity as 'psychedelic therapy'. It is assumed that positive outcomes via psychedelic therapy critically depend on a synergistic relationship between drug-induced brain and mind plasticity and supportive contextual factors (Carhart-Harris et al., 2018; Carhart-Harris and Friston, 2019). These contextual factors have been referred to as 'set and setting' (Leary et al., 1963) or 'extrapharmacological'- highlighting elements beyond the drug that contribute to relevant outcomes (Hartogsohn, 2016).
The proposed experiment is a double-blind, randomized between-subjects 2 x 2 factorial study in 120 volunteers who experience low psychological well-being at baseline and have limited prior experience with psychedelics (1:1:1:1, n = 30 per condition). The main aim of the study is to assess the contribution of a select number of pre-defined contextual variables (both 'set' and 'setting') on the nature and trajectory of effects linked to a single dosing session with either psilocybin (oral, 25mg) or placebo (oral, inert).
The study will have four primary outcomes, two pertaining to mental health, namely: changes in psychological well-being - as measured via the Warwick-Edinburgh Mental Wellbeing Scales (WEMWBS), from baseline to 4 weeks post dosing session (primary endpoint) and changes in the Watts Connectedness Scale (WCS) at consistent timepoints. The two primary outcomes indexing the quality of the acute experience will be: Emotional Breakthrough - measured via mean scores on the Emotional Breakthrough Inventory (EBI), and Challenging experience (CE) - defined and measured here as scores on the following four sub-factors of the Challenging Experience Questionnaire (CEQ): fear, insanity, isolation, and paranoia.