Association of affective temperaments measured by TEMPS-a with cognitive deficits in patients with bipolar disorder

Affective temperaments such as cyclothymia, which may be the fundamental substrates for bipolar disorder and bipolar II in particular, have been reported to be associated with abnormalities in the regions that are related to cognitive deficits in bipolar disorder. However, few studies have examined the effects of affective temperaments on neuropsychological performance in individuals with bipolar disorder.

In a six-week prospective study, we administered Chinese version of TEMPS-A (Temperament Evaluation of Memphis, Pisa, San Diego-Autoquestionnair) to 93 patients with bipolar I depression, 135 patients with bipolar II depression, and 101 healthy controls. Cognitive function was assessed with a battery of neuropsychological tasks, including attention, processing speed, set shifting, planning, verbal working memory, verbal fluency, and visual spatial memory. Mixed-effects statistical models were used to assess the effects of affective temperaments on cognitive function.

Bipolar patients with hyperthymic temperament showed greater cognitive deficits in set shifting (p=0.05) and verbal working memory (p=0.026) than did bipolar patients with non-predominant temperaments (predominant temperament was defined as one standard deviation above the mean). The differences in estimated marginal means were -0.624 (95% CI, -1.25 to 0) and -0.429 (95% CI, -0.81 to -0.05), respectively. Significant temperament X bipolar subtype interaction effects were observed for set shifting (Wald X(2)=18.161, p<0.001), planning (Wald X(2)=7.906, p=0.048), and visual spatial memory (Wald X(2)=16.418, p=0.001).

The anxious temperament was not evaluated.

Our data suggest that hyperthymic temperament may be associated with cognitive deficits in some specific domains in bipolar disorder; and that the effect of temperaments may be different across subtypes of bipolar disorder.