Study infomation

Research questions Does psilocybin-assisted psychotherapy (PAP) lead to greater reductions in depressive symptoms compared to placebo? Are acute experiences of Oceanic Boundlessness (OCB) associated with greater reductions in depressive symptoms? Does Oceanic Boundlessness mediate increases in connectedness to nature following psilocybin-assisted psychotherapy? Hypotheses H1. Participants in the psilocybin arm will show greater reductions in depressive symptoms (MADRS scores) from baseline (V2) to post-treatment follow-ups (V6, and V7) compared to those in the placebo arm. H2. Greater acute Oceanic Boundlessness (OCB), measured immediately following dosing (V4), will be associated with differential trajectories of depressive symptom change across follow-up (from V2 baseline to V6 week 3 , to V7 week 6). Specifically, higher OCB is expected to moderate longitudinal reductions in MADRS scores over time and may also be associated with greater overall symptom improvement. H3.Specific subscales of Oceanic Boundlessness, measured immediately following dosing (V4), will differentially predict reductions in depressive symptoms with one or more subscales predicted to be associated with greater reductions in depressive symptoms from baseline (V2) to follow-up (V6 and V7). H4. Psilocybin-assisted psychotherapy will lead to increased connectedness to nature from baseline (V2) to follow-up assessments at 3 weeks (V6) and 6 weeks (V7), relative to placebo. H5. Acute Oceanic Boundlessness (V4) will mediate the relationship between treatment allocation and increases in connectedness to nature at follow-up (V6 and V7)