Neurocognitive Impairment in Bipolar Patients With and Without History of Psychosis

Objective: Little is known regarding the impact of psychotic symptoms on the cognitive functioning of bipolar patients. Findings from previous reports are controversial and mainly focused on current psychotic symptoms. The main aim of this study was to ascertain whether the history of psychotic symptoms was associated with greater cognitive impairment in euthymic bipolar patients.

Method: Sixty-five euthymic bipolar disorder patients (DSM-IV criteria; 35 with a history of psychotic symptoms and 30 without such a history) were assessed through a neuropsychological battery targeting attention, psychomotor speed, verbal memory, and executive functions. Thirty-five healthy controls were also included in the study in order to compare the neuropsychological performance among groups. Multivariate analysis of covariance was performed controlling for the effect of residual depressive symptoms as a covariate. The study was conducted from June 2005 to June 2006.

Results: Bipolar patients with a history of psychotic symptoms showed a higher number of manic episodes and more hospitalizations than patients without such a history (both p < .001). Regarding neuropsychological performance, patients with a history of psychotic symptoms performed more poorly than those without such a history or controls in all verbal memory measures (p < .005). Furthermore, patients with a history of psychotic symptoms were more impaired on tasks related to executive functions compared to healthy controls (p < .05). History of psychotic symptoms was found to be a predictor of verbal memory impairment.

Conclusions: Our findings suggest that the history of psychotic symptoms may partly account for the cognitive dysfunctions seen in euthymic bipolar patients, especially with regard to persistent verbal memory dysfunction, as well as with some executive dysfunctions.