Affective lability may distinguish BPD from bipolar disorder patients
MedWire News: Patients with bipolar disorder differ from those with borderline personality disorder (BPD) regarding patterns of affective lability, US researchers report.
"Bipolar disorder may be difficult to distinguish clinically from BPD, and there is recent evidence that patients with BPD are frequently misdiagnosed to have bipolar disorder," explain D Bradford Reich (Harvard Medical School, Boston, Massachusetts) and team.
However, they add that "previous research has suggested that the affective lability of patients with bipolar disorder and BPD may have different characteristics."
To investigate further, the team studied 29 women, aged a mean of 31.7 years, who met Revised Diagnostic Interview for Borderlines and DSM-IV criteria for BPD, and 25 women, aged a mean of 33.4 years, who met DSM-IV criteria for bipolar II disorder or cyclothymia.
All of the participants were assessed for affective instability using the self-report Affective Lability Scale (ALS), the self-report Affect Intensity Measure (AIM), and the clinician-administered Affective Lability Interview for Borderline Personality Disorder (ALI-BPD).
The researchers found that patients with bipolar disorder had a significantly higher mean score on the ALS euthymia-elation subscale than did BPD patients, at 1.5 versus 1.0, but a significantly lower mean score on the ALS anxiety-depression subscale, at 1.6 versus 2.0.
Patients with bipolar disorder also had a significantly higher mean total AIM score than BPD patients, at 2.1 versus 1.7, as well as a significantly higher mean score on the AIM positive emotion subscale, at 1.6 versus 0.9.
Regarding shift frequency on the ALI-BPD, BPD patients had significantly less frequent affective shifts between euthymia and elation, and between depression and elation, than did bipolar disorder patients, and significantly more frequent shifts between euthymia and anger, anxiety and depression, and depression and anxiety.
In terms of shift intensity on the ALI-BPD, BPD patients had significantly less intense shifts between euthymia and elation and between depression and elation than did bipolar disorder patients, and significantly more intense shifts between euthymia and anxiety, euthymia and anger, anxiety and depression, and depression and anxiety.
Reich and team conclude in Comprehensive Psychiatry: "Results of our study demonstrate clear differences between borderline and bipolar subjects in both self-report and clinician-administered… assessments of affective lability."
They add that "future research should attempt to replicate results of the study in a larger sample, containing both male and female subjects."
By Mark Cowen