The early course of depression: a longitudinal investigation of prodromal symptoms and their relation to the symptomatic course of depressive episodes.

The present study explored longitudinal evidence for prodromal symptoms of depression episodes. A model based on previous findings of the relations between prodromal and residual symptoms was described and used to generate hypotheses tested in this study. Data were analyzed from 160 participants from the Cognitive Vulnerability to Depression (CVD) project (L. Alloy & L. Abramson, 1999) who experienced an episode of depression during the prospective follow-up period and 60 CVD participants who did not. Congruent with the hypothesis, individuals who subsequently developed an episode of depression experienced significantly greater numbers of depression symptoms in the period of time leading up to the acute episode compared with those who did not develop a depressive episode. Seven depression symptoms were particularly likely to appear before the onset of an acute episode. Furthermore, all 3 predictions from the model were supported: the durations of prodromal and residual phases were correlated, the prodromal and residual symptom profiles were quite similar, and the order of symptom onset was significantly and highly negatively correlated with the order of symptom remission. Additionally, residual symptom profiles were similar to subsequent prodromal symptom profiles in individuals who experienced more than 1 depressive episode. These findings are discussed in terms of the importance of understanding the earliest prodromal symptoms to appear and their relation to the symptomatic course of depression episodes. Implications for early intervention are also discussed.