Clinical variables and implications of the personality on the outcome of bipolar illness: a pilot study

Outcome in bipolar patients is affected by comorbidity. Comorbid personality disorders are frequent and may complicate the course of bipolar illness. This pilot study examined a series of 40 euthymic bipolar patients (DSM-IV criteria) (bipolar I disorder 31, bipolar II disorder 9) to assess the effect of clinical variables and the influence of comorbid personality on the clinical course of bipolar illness. Bipolar patients with a diagnosis of comorbid personality disorder (n = 30) were compared with "pure" bipolar patients (n = 10) with regard to demographic, clinical, and course of illness variables. Comorbid personality disorder was diagnosed in 75% of patients according to ICD-10 criteria, with obsessive-compulsive personality disorder being the most frequent type. Sixty-three per cent of subjects had more than one comorbid personality disorder. Bipolar patients with and without comorbid personality disorder showed no significant differences regarding features of the bipolar illness, although the group with comorbid personality disorder showed a younger age at onset, more depressive episodes, and longer duration of bipolar illness. In subjects with comorbid personality disorders, the number of hospitalizations correlated significantly with depressive episodes and there was an inverse correlation between age at the first episode and duration of bipolar illness. These findings, however, should be interpreted taking into account the preliminary nature of a pilot study and the contamination of the sample with too many bipolar II patients.