Type A behavior pattern and hyperthymic temperament: possible association with bipolar IV disorder.

BACKGROUND

Type A behavior pattern (TABP) has traditionally been reported to be associated with coronary heart disease and, more recently, several researchers have examined its association with depression and bipolar disorder. According to Akiskal and Pinto (1999), there are 2 subtypes of bipolar spectrum which are not associated with manic or hypomanic state. These are bipolar II1/2 (depression in those who have cyclothymic temperament) and bipolar IV (depression in those who have hyperthymic temperament). Our hypothesis is that individuals with hyperthymic temperament may have a tendency towards TABP.

OBJECTIVES

The purposes of the present study are to investigate the association between TABP and hyperthymic temperament and to determine other biological factors associated with TABP.

METHODS

Fifty healthy subjects were assessed for TABP and hyperthymic temperament by self-rating scales, daily activity, sleep time and illuminance by actigraphy, and central serotonergic function via the neuroendocrine challenge test. Serum brain-derived neurotrophic factor (BDNF) levels were also measured.

RESULTS

Stepwise regression analysis indicated that hyperthymic temperament score was positively associated with TABP scores and both sleep time and snooze time were negatively associated with TABP scores. BDNF levels were not associated with TABP scores.

CONCLUSIONS

These findings suggest that individuals with hyperthymic temperament may have a tendency towards TABP, and TABP persons may have short sleep time and short snooze time. Although further studies are required to investigate the association between TABP and affective disorders, the present findings clearly indicate the association between TABP and hyperthymic temperament, which may be associated with bipolar IV disorder. Taking TABP as a risk factor of cardiovascular events into consideration, this association between TABP and bipolar IV disorder may account for the well-known cardiovascular mortality in bipolar disorder.