Temperament can be assessed along several dimensions that define qualitatively different aspects of affective regulation. Different sets of genes may be associated with each of these dimensions of temperament, which would suggest that the different affective temperaments might define subtypes of BD with different clinical features and courses of illness. Several studies provide support for this idea. For example, studies of temperament suggest that some forms of major depression with hyperthymic temperament may be more related to BD (9,20). Different temperaments within BD have also been associated with different rates of relapse and response to antidepressants (20–21). Finally, different temperaments in BD have been shown to be associated with different clinical courses (22–23).
