Comparison of affective instability in borderline personality disorder and bipolar disorder using a self-report...

This study used a new self-report instrument to measure frequency and intensity of nine dimensions of affective instability, as well as the extent to which affective instability was interpersonal, in subjects endorsing elevated features of BPD and bipolar disorder.

Subjects were 818 students enrolled in a state university. The study used self-report instruments to identify 21 participants with elevated features of mania and 30 subjects with significant BPD features. In addition, subjects completed a new self-report instrument to measure affective instability, the Affective Lability Questionnaire for Borderline Personality Disorder (ALQ-BPD).

Aggregate frequency and intensity scores, as well as the total scores on the ALQ-BPD, were significantly higher for subjects with elevated borderline traits than subjects with elevated bipolar traits. Subjects with borderline traits reported significantly more frequent affective shifts on seven of nine dimensions of the ALQ-BPD. Subjects with borderline traits reported significantly more intense affective shifts on two of nine dimensions. Both groups reported affective instability that was less than 50% reactive to interpersonal events, but subjects with borderline traits reported affective instability that was significantly more interpersonal than that reported by subjects with bipolar traits.

The affective instability associated with symptoms of BPD and bipolar disorder has different profiles, particularly with respect to frequency. Borderline affective instability appears more interpersonal than the affective instability associated with bipolar symptoms.