Neurocognitive Impairment and Psychosis in Bipolar I Disorder During Early Remission From an Acute Episode of Mood Disturbance

Objective: Recent studies have reported greater neurocognitive impairment in euthymic bipolar disorder patients with a history of psychosis relative to patients without such a history. To further explore the relation between psychosis and cognitive dysfunction in bipolar disorder, the current study examined the cognitive functioning of patients during early remission from a discrete episode of mood disturbance. The study aimed to determine whether the presence of psychosis during inpatient hospitalization was associated with greater cognitive impairment at the time of hospital discharge.

Method: Fifty-nine inpatients who met DSM-IV criteria for bipolar disorder (24 admitted with psychosis, 35 admitted without psychosis), ages 18-59 years, completed a neuropsychological battery and mood measures 24-48 hours before discharge. The cognitive battery included standardized tests of IQ, attention and working memory, visual memory, verbal memory, and executive functioning.

Results: A multivariate analysis of variance detected group differences on measures of verbal memory (P‘ ‰<‘ ‰.001) and executive functioning (P‘ ‰<‘ ‰.003), using mood measures and previous number of psychiatric admissions as covariates. Post hoc analysis of between-subjects effects revealed significantly poorer performance on the California Verbal Learning Test-Second Edition, logical memory subtest from Wechsler Memory Scale-Revised, Stroop Word/Color Interference test, and the Wisconsin Card Sorting Test for patients who were admitted to the hospital with psychosis. These results remained significant after matching the groups for past psychosis, with the exception of the logical memory subtest.

Conclusions: The results of this study indicate that patients with bipolar disorder who were admitted to the hospital due to psychosis exhibited significantly more severe cognitive impairment at the time of discharge than patients admitted for an acute mood disturbance without psychosis. These findings may be important for improving discharge planning and the development of more effective outpatient services.

Submitted: August 24, 2008; accepted January 2, 2009.

Online ahead of print: November 17, 2009.

Corresponding author: Boaz Levy, PhD, Department of Psychiatry, Harvard Medical School, McLean Hospital, 115 Mill St, Belmont, MA 02478 (boaz_levy@hms.harvard.edu).