Atypicality in primary depressive illness: a preliminary survey.

Primary depressive illness comprises a wide variety of clinical presentations which may represent disorders with different underlying biology, life course, and treatment response. In order to explore possible correlates of such clinical heterogeneity, we have constructed a rating scale for atypical depressive illness. Forty-four patients, all meeting Research Diagnostic Criteria for primary major depressive disorder were evaluated for atypicality using the scale. Within this group, atypicality was found to be characterized by lack of clearly encapsulated episodes of depression, a high degree of character pathology, prominent anxiety, somatization, and neurotic symptoms, and a past history of diagnostic confusion. Atypical patients were younger than typicals, more likely to be unipolar or bipolar II, and more often hospitalized, despite lower frequency of depressive episodes. While both typical and atypical groups showed decreased REM latency and increased urinary-free cortisol, they differed in measures related to noradrenergic metabolism, monoamine oxidase activity, and slow wave sleep. Preliminary results also raised the question of possible differences in treatment response between typical and atypical patients.