Comorbidity of bipolar and personality disorder

The aims of this study were to determine the prevalence of personality disorder in a sample of patients with well-documented bipolar disorder, and to assess the effects of comorbidity.

The sample (n = 42) was drawn from patients currently case-managed within a community treatment program who fully met DSM-IV criteria for bipolar I disorder. The International Personality Disorder Examination, a structured interview, was used to diagnose personality disorder. The Brief Symptom Inventory assessed overall levels of psychological symptoms.

Seven of the 13 men (55%) in the sample had 10 personality disorder diagnoses and 12 of the 29 women (41%) had 28 diagnoses, an overall prevalence of 45%. Hospital admission rates and all measures of psychological symptoms and impairment were significantly elevated in the comorbid group, who found medication significantly less helpful.

Comorbid personality disorder was common in the sample studied, which was representative of Australian patients treated in public community psychiatry programs. However, only three (7%) had a personality disorder diagnosis recorded in their case notes, reflecting clinicians' reluctance to apply what is widely viewed as a pejorative and therapeutically nihilistic label. New treatments for personality disorder have proven effective within both public and private psychiatric settings, so that underdiagnosis represents undertreatment. The findings suggest that clinicians should be more vigilant for comorbid personality and bipolar disorder, and less reluctant to diagnose it.