Sex differences in cognitive functioning in patients with bipolar disorder who recently recovered from a first episode of mania: data from the Systematic Treatment Optimization Program for Early Mania (STOP-EM).

BACKGROUND

Studies investigating bipolar disorder (BD) showed that healthy patterns of sex differences in cognitive functioning are altered within this population, but is it unknown whether these alterations are present in BD patients early in their course of illness.

METHODS

Patients with bipolar I disorder (36 males, 38 female), who had recently experienced their first manic or mixed episode were tested along with healthy controls (39 males, 59 females) similar in age, sex and premorbid IQ. Cognitive function was assessed through a comprehensive neuropsychological test battery.

RESULTS

Significant group effects were found in a majority of administered tests (p<0.05) with patients performing worse than healthy controls. Significant sex effects (p<0.05) were observed on tasks of spatial working memory and sustained attention, with males performing better than females. No significant group by sex interaction was found in any of the tasks administered.

LIMITATIONS: The cognitive battery employed in this study may not have been optimally sensitive in detecting sex differences.

CONCLUSIONS

The results suggest that unlike patients with long standing multi-episode BD or schizophrenia, healthy cognitive sex differences are maintained in patients with early BD, following recovery from a first-episode of mania. These findings highlight the progressive nature of the illness and provide justification for an early intervention.