67,79 Table II Frequency of borderline personality disorder (BPD) in individuals with bipolar disorder. Across all studies, the frequency of BPD in the 1255 patients with bipolar disorder was 16.0% (n=201). In the 12 studies of 598 patients with bipolar I disorder, the prevalence of BPD was 10.7% (n=64). In the seven studies of 261 patients with bipolar II disorder, the prevalence of BPD was twice as high (22.9%, n=60). Only two groups of investigators reported data on both bipolar I and bipolar II disorder. In two separate reports Vieta et al67,68 found that BPD was diagnosed twice as frequently in patients Inhibitors,research,lifescience,medical with bipolar II disorder than bipolar I disorder (12.5%

vs 6.2%). While they did not statistically compare these prevalence rates, we conducted a chi-square test based on the raw data provided in the two articles and found that the

difference was not STA4783 significant (X2=1.71, ns). Similarly, Zimmerman et al79 reported a higher prevalence of BPD in patients Inhibitors,research,lifescience,medical with bipolar II disorder, but the difference was not significant. Thus, while the summary across studies suggests a significantly higher rate of BPD in patients with bipolar II than bipolar I disorder, the only two studies that allowed for a direct comparison did not find a significant difference between the two groups. In the seven studies of 389 patients that either did not specify the type of bipolar Inhibitors,research,lifescience,medical disorder, or did not present results separately for bipolar I and bipolar II disorder, the rate of BPD was Inhibitors,research,lifescience,medical similar to the rate in patients with bipolar II disorder (20.8%, n=81). Nine studies indicated that they assessed patients upon presentation for treatment or when the patients were symptomatic.71,72,77,79-84 Eight of these nine studies were of bipolar II disorder or unspecified bipolar disorder. Across these eight studies the prevalence of BPD was 22.5% (80/355), little different than the prevalence for the entire group of patients Inhibitors,research,lifescience,medical with bipolar II disorder or unspecified bipolar disorder. This suggests that state effects did not have a robust influence on the prevalence of BPD. Only one study directly

examined the impact of psychiatric state on else the prevalence of BPD. Peselow et al40 interviewed patients upon presentation for treatment of hypomania, and again 8 weeks later after symptom resolution, and found a small decrease in the prevalence of BPD (23.4% vs 17.0%). We are not aware of any comparable studies that interviewed bipolar patients while depressed and again after improvement in depressive symptoms. Is borderline personality disorder the most frequent personality disorder in patients with bipolar disorder? Fifteen studies examined the full-range of personality disorders in patients with bipolar disorder.40,63,67,68,80,82,85,93 In only four of the 15 studies BPD was the most frequent diagnosis.