Affective lability in bipolar disorder and borderline personality disorder

The boundaries between the affective instability in bipolar disorder and borderline personality disorder have not been clearly defined. Using self-report measures, previous research has suggested that the affective lability of patients with bipolar disorder and borderline personality disorder may have different characteristics.

We assessed the mood states of 29 subjects meeting Revised Diagnostic Interview for Borderlines and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for BPD and 25 subjects meeting DSM-IV criteria for bipolar II disorder or cyclothymia using the Affective Lability Scale (ALS), the Affect Intensity Measure (AIM), and a newly developed clinician-administered instrument, the Affective Lability Interview for Borderline Personality Disorder (ALI-BPD). The ALI-BPD measures frequency and intensity of shifts in 8 affective dimensions. Subjects in the borderline group could not meet criteria for bipolar disorder; subjects in the bipolar/cyclothymia group could not meet criteria for BPD.

Patients in the bipolar group had significantly higher scores on the euthymia-elation subscale of the ALS; patients in the BPD group had significantly higher scores on the anxiety-depression subscale of the ALS. Patients with bipolar disorder had significantly higher total AIM scores and significantly higher score on the AIM positive emotion subscale. In terms of frequency, patients in the borderline group reported the following: (1) significantly less frequent affective shifts between euthymia-elation and depression-elation on the ALI-BPD and (2) significantly more frequent shifts between euthymia-anger, anxiety-depression, and depression-anxiety. In terms of intensity, borderline patients reported the following: (1) significantly less intense shifts between euthymia-elation and depression-elation on the ALI-BPD and (2) significantly more intense shifts between euthymia-anxiety, euthymia-anger, anxiety-depression, and depression-anxiety.

The affective lability of patients with borderline and bipolar II/cyclothymic can be differentiated with respect to frequency and intensity using both self-report and clinician-administered measures.