The impact of cognitive impairment, neurological soft signs and subdepressive symptoms on functional outcome in bipolar disorder.

BACKGROUND

Cognitive impairments and subsyndromal depressive symptoms are present during euthymic periods of bipolar disorder (BD). Most studies have determined that cognitive impairments and residual depressive symptoms have major impacts on psychosocial functioning. The aim of the present study was to identify the major factor responsible for low psychosocial functioning in a subgroup of patients with BD despite clinical recovery.

METHODS

Sixty patients with bipolar I disorder and 41 healthy subjects were enrolled in this study. Cognitive performance, neurological soft signs (NSSs), psychosocial functioning, residual mood symptoms and illness characteristics were assessed. Using the median value of the Functioning Assessment Short Test (FAST) as the cut-off point, the patients were divided into two groups, high- (n=29) or low-functioning (n=31), and they were compared based on total NSS, residual depressive symptoms, cognitive performance and clinical variables.

RESULTS

Performances on the verbal memory tests and social functioning were significantly worse in the euthymic patients with BD. Increased rates of NSS were identified in the patients compared with the normal controls. The low-functioning patients performed significantly worse on verbal memory, and their NSS and residual depressive symptoms were significantly higher compared to high-functioning patients. In the regression analysis, subsyndromal depressive symptoms and verbal learning measures were identified as the best predictors of psychosocial functioning.

LIMITATIONS

The patients were artificially separated into two groups based on a FAST score cut-off.

CONCLUSIONS

In this study, residual depressive symptoms and verbal memory impairments were the most prominent factors associated with the level of functioning.