Are atypical depression, borderline personality disorder and bipolar II disorder overlapping manifestations of a common cyclothymic diathesis?

The constructs of atypical depression, bipolar II disorder and borderline personality disorder (BPD) overlap. We explored the relationships between these constructs and their temperamental underpinnings. We examined 107 consecutive patients who met DSM-IV criteria for major depressive episode with atypical features. Those who also met the DSM-IV criteria for BPD (BPD+), compared with those who did not (BPD-), had a significantly higher lifetime comorbidity for body dysmorphic disorder, bulimia nervosa, narcissistic, dependent and avoidant personality disorders, and cyclothymia. BPD+ also scored higher on the Atypical Depression Diagnostic Scale items of mood reactivity, interpersonal sensitivity, functional impairment, avoidance of relationships, other rejection avoidance, and on the Hopkins Symptoms Check List obsessive-compulsive, interpersonal sensitivity, anxiety, anger-hostility, paranoid ideation and psychoticism factors. Logistic regression revealed that cyclothymic temperament accounted for much of the relationship between atypical depression and BPD, predicting 6 of 9 of the defining DSM-IV attributes of the latter. Trait mood lability (among BPD patients) and interpersonal sensitivity (among atypical depressive patients) appear to be related as part of an underlying cyclothymic temperamental matrix.