ABSTRACT
Self-stigma profoundly impacts psychological well-being in individuals with bipolar disorder, yet the mechanisms underlying this relationship remain unclear. This study examined whether self-compassion mediates the relationship between self-stigma and psychological well-being, whether treatment adherence moderates this mediating pathway, and whether age moderates the direct relationship. A cross-sectional study was conducted with 121 outpatients diagnosed with Bipolar Type I Disorder receiving care at two hospitals in Eastern Türkiye between January 2024 and February 2025. Participants completed validated measures of self-stigma, self-compassion, and psychological well-being during clinical remission. Data were analysed using mediation, moderated mediation, and simple moderation models with bootstrap procedures. Self-stigma demonstrated a strong negative total effect on well-being. Self-compassion partially mediated this relationship, explaining 27% of the total effect. Critically, moderated mediation analysis revealed that treatment adherence significantly altered the strength of this mediating pathway. Among individuals with poor treatment adherence, self-stigma more severely compromised self-compassion, resulting in a substantially stronger indirect effect on well-being compared to those with good adherence. The difference between these conditional indirect effects was statistically significant. Additionally, age moderated the direct relationship between self-stigma and well-being, with younger adults showing greater vulnerability than older adults, though age did not moderate the self-compassion pathway. These findings identify self-compassion as a key but conditionally effective protective mechanism against self-stigma. Treatment adherence emerges as a critical factor that preserves this protective mechanism, suggesting that adherence promotion represents both a clinical and psychosocial intervention target for mental health nurses.