Group-based psychosocial interventions reduce internalized stigma in psychiatric disorders: ISMI-focused systematic review.

Background: Internalized stigma negatively impacts recovery outcomes, quality of life, and self-concept among individuals with psychiatric diagnoses. Group-based psychosocial interventions have been proposed as effective stigma-reduction strategies, but their impact across diverse populations remains under-evaluated. Objective: This systematic review synthesizes global evidence on the effectiveness of group-based interventions in reducing internalized stigma in adult psychiatric populations, with a focus on studies using the Internalized Stigma of Mental Illness (ISMI) scale. Methods: Following PRISMA 2020 guidelines, we searched PubMed, PsycINFO and Web of Science, and additionally screened full-text platforms (SpringerLink, ScienceDirect, SAGE Journals, and Wiley Online Library), for studies published between 2003 and 2025. Inclusion criteria required adult psychiatric populations, group-based interventions, and internalized stigma as a primary outcome. Study selection, risk of bias assessment, and data extraction were performed independently by two reviewers (US and GOC). Results: Ten studies [n= 1,088], across five countries, met inclusion criteria, including randomized controlled trials and pre-post designs. Most studies reported significant reductions in ISMI scores post-intervention, particularly in the domains of stereotype endorsement and social withdrawal. Culturally adapted interventions in China, Poland, and Spain demonstrated feasibility and impact, though subscale reliability varied regionally. Conclusion: Group-based psychosocial interventions may help reduce internalized stigma in psychiatric populations within an ISMI-based evidence base. The ISMI scale is, to this day, among the most frequently used instrument, though cultural adaptation of subscales such as stigma resistance remains a concern.