A PROSPECTIVE 12-YEAR STUDY OF SUBSYNDROMAL AND SYNDROMAL DEPRESSIVE SYMPTOMS IN UNIPOLAR MAJOR DEPRESSIVE-DISORDERS

Background: Investigations of unipolar major depressive disorder (MDD) have focused primarily on major depressive episode remission/recovery and relapse/ recurrence. This is the first prospective, naturalistic, longterm study of the weekly symptomatic course of MDD. Methods: The weekly depressive symptoms of 431 patients with MDD seeking treatment at 5 academic centers were divided into 4 levels of severity: (1) depr essive symptoms at the threshold for MDD; (2) depressive symptoms at t he threshold for minor depressive or dysthymic disorder (MinD); (3) su bsyndromal or subthreshold depressive symptoms (SSDs),below the thresh olds for MinD and MDD; and (4) no depressive symptoms. The percentage of weeks at each level, number of changes in symptom level, and medica tion status were analyzed overall and for 3 subgroups defined by mood disorder history. Results: Patients were symptomatically ill in 59% of weeks. Symptom levels changed frequently (1.8/y), and 9 of 10 patient s spent weeks at 3 or 4 different levers during follow-up. The MinD (2 7%) and SSD (17%) symptom levels were more common than the MDD (15%) s ymptom level. Patients with double depression and recurrent depression had more chronic symptoms than patients with their first lifetime maj or depressive episode (72% and 65%, respectively, irs 46% of follow-up weeks). Conclusion: The long-term weekly course of unipolar MDD is do minated by prolonged symptomatic chronicity. Combined MinD and SSD lev el symptoms were about 3 times more common (43%) than MDD level sympto ms (15%). The symptomatic course is dynamic and changeable, and MDD, M inD, and SSD symptom levels commonly alternate over time in the same p atients as a symptomatic continuum of illness activity of a single cli nical disease.