Background. Previous work suggests that subthreshold depression and subthreshold (hypo)mania are common, although little is known about the prognosis in terms of transition to clinical disorder. This paper presents data on the temporal relationship between subthreshold and clinical expression of mood phenotypes.
Method. In a random general population sample of 7076 individuals, symptoms of depression and (hypo)mania were measured with the Composite International Diagnostic Interview (CIDI) at baseline, after 1 year, and 2 years later.
Results. At baseline, the lifetime prevalences of depressive and (hypo)manic symptoms were 17·2% and 1·2% respectively. Predictive values of mood symptoms for a DSM-III-R mood disorder ranged from 14·3% to 50%. (Hypo)manic mood symptoms had much higher predictive values than unipolar manifestations, not only for bipolar disorder but also for major depression.
Conclusions. The subthreshold expressions of depression and (hypo)mania are prevalent and continuous with more severe clinical states. The cross-prediction of mood symptoms may support a continuum from depressive to (hypo)manic symptoms. The high predictive value of (hypo)manic symptoms for mood disorders suggests that the experience of (hypo)manic symptoms is a stronger indicator of vulnerability for mood dysregulation than the experience of depressive symptoms.