Long-term outcome of cognitive impairment in bipolar disorder

To evaluate the longitudinal course and outcome of cognitive deficits and their clinical correlates in bipolar disorder.

One hundred thirteen participants (68 patients and 45 healthy controls) were assessed by the means of a neuropsychological battery targeting attention, psychomotor speed, verbal memory, and executive functions at baseline: 68 euthymic outpatients with a DSM-IV diagnosis of bipolar disorder (53 bipolar I and 15 bipolar II) were enrolled at the Bipolar Disorder Unit of the Hospital Clinic of Barcelona. Forty-five patients completed the follow-up. The assessments started in February 1999 and finished in July 2010. The primary outcome of the study was the change in the neuropsychological performance in the patient group.

Repeated-measures analyses showed significant effects of time in 2 cognitive domains: attention and executive functions. Attention slightly improved (P = .043) but executive function worsened (P = .001). Regression analyses showed that the duration of illness and baseline subdepressive symptoms were associated with poor performance in executive function. Subdepressive symptoms at endpoint were associated with poor functioning. The best predictor of low functioning was verbal memory dysfunction at baseline.

The cognitive impairment remained stable across the follow-up period in many measures assessed except for a worsening of executive measures, which have been found to be associated with the duration of illness and subdepressive symptoms.