A systematic review of participant diversity in psychedelic-assisted psychotherapy trials

A lack of diverse and representative participant samples in mental health intervention research perpetuates mental health disparities. This issue has become a salient concern in studies of psychedelic-assisted psychotherapy (PAT), which is emerging as a promising mental health intervention. This systematic review evaluates the reporting, representation, and analysis of participant sociodemographic characteristics in randomized controlled trials (RCTs) of PAT. A total of 21 RCTs of psilocybin- and 3,4-methylenedioxy methamphetamine (MDMA)-assisted therapies (N = 1034) are summarized. Participants' gender (100%) and race or ethnicity (76%) were frequently reported, with socioeconomic status (SES) sometimes (57%) reported using heterogeneous metrics. Sexual orientation (9.5%) and immigration status (4.8%) were rarely reported, and no studies reported gender identity. Compared to their representation in the US population and non-psychedelic clinical trials, Black/African-American participants (2.2%) and Hispanic/Latino participants (7.2%) were significantly underrepresented in PAT RCTs. MDMA trials enrolled more diverse participant samples than psilocybin trials. Analyses on treatment effects based on demographic variables were virtually nonexistent. These findings underscore the need for more inclusive recruitment strategies, along with more rigorous reporting, to improve the generalizability of PAT research.