Rejection Sensitivity Among Adults with Comorbid Borderline Personality Disorder and Attention-Deficit/Hyperactivity Disorder

Background: Rejection sensitivity (RS)—anxious expectations of interpersonal rejection—is consistently elevated in borderline personality disorder (BPD), but evidence in attention-deficit/hyperactivity disorder (ADHD), particularly in adults, remains limited and mixed. We compared RS in adults with comorbid BPD and ADHD versus healthy controls and examined whether ADHD, depressive, and anxiety symptoms were independently associated with RS.Methods: This cross-sectional case-control study included 84 adults: 40 with comorbid BPD and ADHD and 44 age- and sex-matched healthy controls. A psychiatrist established diagnoses using structured DSM-5 interviews. Participants completed the Rejection Sensitivity Questionnaire (RSQ), Adult ADHD Self-Report Scale (ASRS), Beck Depression Inventory, and Beck Anxiety Inventory. Group differences were examined with an adjusted general linear model, and hierarchical regression assessed the incremental contributions of anxiety, depressive, and ADHD symptoms beyond group status and sociodemographic variablesResults: RSQ scores were higher in the comorbid group than in controls (11.52 ± 3.77 vs. 8.33 ± 3.01; p < .001, d = 0.94), and this difference remained after adjustment for sociodemographic variables, F(1,79) = 27.25, p < .001, partial η² = .256. Group status and ASRS score were independently associated with RSQ score, whereas anxiety and depressive symptoms were not; ASRS score explained an additional 3.2% of variance.Conclusions: [SA1.1][eC1.2]Adults with comorbid BPD and ADHD showed elevated rejection sensitivity, with ADHD symptom severity making a modest additional contribution beyond sociodemographic, anxiety, and depressive symptoms. RS may be clinically relevant in this population, but longitudinal studies are needed before causal or treatment implications can be drawn.