Symptoms of anorexia nervosa and bulimia nervosa have differential relationships to borderline personality disorder symptoms.

Eating disorders (EDs) and borderline personality disorder (BPD) are highly comorbid. BPD is characterized by the presence of at least five of nine symptoms. Given the number/variety of emotional and interpersonal symptoms that comprise BPD, some BPD traits may relate to EDs, whereas others may not be associated. This study examined relationships between BPD symptoms and symptoms of bulimia nervosa (BN) and anorexia nervosa (AN), including whether the nine BPD symptoms differentially relate to BN versus AN. Participants were 208 adolescent psychiatric inpatients. BPD symptoms, measured via structured interview, correlated more strongly with self-reported BN than AN symptoms. BN and AN symptoms were greater among individuals who endorsed unstable relationships, affective instability, emptiness, identity disturbance, inappropriate anger, dissociation/paranoia, and suicidal behavior. BN, but not AN symptoms, were higher when impulsivity was endorsed. Avoiding abandonment was neither related to BN nor AN. Affective instability, impulsivity, and anger had substantially larger associations with BN compared to AN, while identity disturbance was more strongly related to AN than BN. Findings provide useful information for targeting specific BPD symptoms to help prevent and reduce co-occurring EDs and BPD and the negative consequences associated with this comorbidity.