Several studies have demonstrated the ability of temperament measures to predict risk for bipolar spectrum disorders (4,11–14) and to discriminate between affected subjects, normal controls, and healthy relatives of affected subjects (15–18). Although mixed results have been observed for the hyperthymic temperament, with BD subjects scoring highest on this scale in some studies (17,19) and controls scoring highest in others (15–16,18), data suggest that this temperament may be most relevant to the bipolar I (BDI) subtype. The hyperthymic temperament has also demonstrated the ability to distinguish controls from unaffected relatives, indicating an ability to detect latent genetic vulnerability (15,18). In a prospective study on the offspring and siblings of BD patients, hyperthymic and dysthymic temperaments were present before a superimposed mood episode developed (14), further suggesting that the hyperthymic temperament may be particularly associated with a genetic vulnerability for BD.
