Lee and Vaillancourt’s (2023) longitudinal study on the comorbidity of eating disorders and borderline personality disorder (BPD) identifies bullying as a significant environmental risk factor for the development of either or both disorders. Among 14 assessed risk factors, bullying stood out as the most potent: its elimination was projected to reduce the incidence of eating disorders by 66% and BPD by 38%.

In addition to bullying, sociocultural and gender-based factors also play a significant role. Lee and Vaillancourt (2023) report that girls are more frequently diagnosed with eating disorders, whereas LGBTQ+ individuals are more likely to meet criteria for BPD—highlighting how identity-based vulnerabilities intersect with psychiatric risk.

Other interpersonal contributors include personality traits such as impulsivity and emotional instability. These traits may not only predispose individuals to both conditions but also complicate diagnosis. For example, disordered eating behaviors may be misattributed to mood symptoms when in fact they are rooted in underlying personality pathology (Sansone & Sansone, 2010). Notably, these traits may arise from a complex interaction of genetic vulnerability and early relational experiences.--