Non-social cognitive deficits outweigh social ones in bipolar disorder

By Lucy Piper, Senior medwireNews Reporter

Patients with bipolar disorder have relatively greater impairments in non-social cognition than social cognition, whereas the opposite is true for patients with schizophrenia, researchers report.

"Our findings suggest that social cognition may be less of a determinant of functioning in bipolar disorder than it is in schizophrenia," the team comments. "If so, nonsocial cognitive remediation rather than social cognitive intervention may be better suited for bipolar disorder, whereas both types of intervention may be beneficial for schizophrenia."

Junghee Lee, from the David Geffen School of Medicine at UCLA, Los Angeles, California, USA, and colleagues also note that the fact that social cognition was relatively intact in patients with bipolar disorder, whereas non-social cognition was impaired, suggests that "the two domains are not redundant and that social cognitive impairment does not necessarily follow deficits in nonsocial cognition."

The study, published in the American Journal of Psychiatry, involved 68 clinically stable patients with bipolar disorder, 38 clinically stable patients with schizophrenia, and 36 mentally healthy comparison individuals.

On a range of social tasks, measuring facial affect perception, emotional regulation, empathic accuracy, mental state attribution, and self-referential memory, the performance of patients with bipolar disorder was not significantly different from that of comparison individuals.

Patients with schizophrenia, on the other hand, performed significantly worse than those with bipolar disorder and comparison individuals on all tasks, with the largest relative impairments seen for facial affect recognition (average scores 0.71 vs 0.84 and 0.87, respectively) and the sarcasm subscale of The Awareness of Social Inference Test (TASIT; 21.3 vs 26.8 and 28.4, respectively).

While patients with bipolar disorder and comparison individuals showed similar performances for social cognition, significant differences were seen between the two groups for three subdomains of the non-social cognitive tasks, namely attention/vigilance (47.83 vs 54.31), working memory (46.64 vs 52.81), and reasoning and problem solving (43.76 vs 48.94). There was also a difference in visual learning, but this was nonsignificant.

Again, the performances of those with schizophrenia were significantly worse than those in the other two groups.

The researchers note that neither clinical features nor medication status were related to social cognitive performance, and exploratory discriminant analysis showed that social and non-social cognitive performance together discriminate better than either cognitive domain alone.

As one possible explanation for the findings, Lee et al suggest that patients with bipolar disorder may have "compensatory mechanisms that protect social cognitive circuits in the context of impaired non-social cognition and that these compensatory mechanisms are missing in schizophrenia."

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