A systematic review of inclusion of minoritized populations in randomized controlled trials of acceptance and commitment therapy

Acceptance and Commitment Therapy (ACT) is an empirically supported treatment for a variety of clinical concerns and has over 1000 randomized controlled trials (RCTs). ACT may be a potentially effective treatment for racial, sexual orientation and gender diverse people who experience unique stressors related to their identities and higher rates of psychopathology and have unique mental health considerations. Despite this, there remains a lack of inclusion of reporting and inclusion of these communities in psychological research. This lack of inclusion of minority populations limits the generalizability of the findings of RCTs to those populations. Further, although there is a growing number of minority graduate students and trainees, this increased diversity often does not extend to their principal investigators. The current study reviews racial, sexual, and gender minority inclusion of participants as well as of principal investigators in 75 ACT RCTs performed in the United States (n = 10,914). Of these, 73% were White, 11% were Black, 5% were Latine, 3% were Asian, 2% were Native American, 0.4% were Pacific Islander, 0.1% were Middle Eastern, and 3% were multiracial while 1% were reported as Other and another 1% as Unknown. Of the 75 studies reviewed, 5 reported on sexual orientation and 73% of participants were heterosexual, 7% were gay or lesbian, 5% were bisexual, 2% were pansexual, 4% were asexual, 1% were queer, 1% were questioning, and 1% were reported as Other and 7% as Unknown (n = 297). Only two studies reported on gender identity beyond men and women, with one study including all cisgender participants and one study reporting that 2% of participants were nonbinary. Of the 32 PIs that responded, 94% were White, 2% were Mixed, and 2% were Asian. In terms of sexual orientation and gender identity, one PI was gay, one was asexual, and cisgender women authored 26% of studies. These results indicated that despite Black participants being more accurately represented, Latine and Asian participants were largely underrepresented. Regardless of level of representation, the numbers of racial, sexual, and gender minority participants were still limited and therefore conclusions cannot be made about the generalizability of ACT for these populations. Recommendations for more inclusive practices are provided. We discuss limitations to this review and the implications of PI refusal to report their sexual and gender identity.