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, long-term 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) depressive symptoms at the threshold for MDD; (2) depressive symptoms at the threshold for minor depressive or dysthymic disorder (MinD); (3) subsyndromal or subthreshold depressive symptoms (SSDs), below the thresholds for MinD and MDD; and (4) no depressive symptoms. The percentage of weeks at each level, number of changes in symptom level, and medication 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 patients spent weeks at 3 or 4 different levels during follow-up. The MinD (27%) and SSD (17%) symptom levels were more common than the MDD (15%) symptom level. Patients with double depression and recurrent depression had more chronic symptoms than patients with their first lifetime major depressive episode (72% and 65%, respectively, vs 46% of follow-up weeks).


CONCLUSIONS
The long-term weekly course of unipolar MDD is dominated by prolonged symptomatic chronicity. Combined MinD and SSD level symptoms were about 3 times more common (43%) than MDD level symptoms (15%). The symptomatic course is dynamic and changeable, and MDD, MinD, and SSD symptom levels commonly alternate over time in the same patients as a symptomatic continuum of illness activity of a single clinical disease.
Department of Psychiatry, University of California, San Diego, La Jolla 92093-0603, USA.
L L
LL
Judd
H S
HS
Akiskal
J D
JD
Maser
P J
PJ
Zeller
J
J
Endicott
W
W
Coryell
M P
MP
Paulus
J L
JL
Kunovac
A C
AC
Leon
T I
TI
Mueller
J A
JA
Rice
M B
MB
Keller
D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use; D002908:Chronic Disease; D003866:Depressive Disorder / Q000145:classification / Q000175:diagnosis* / Q000188:drug therapy; D019263:Dysthymic Disorder / Q000145:classification / Q000175:diagnosis / Q000188:drug therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012008:Recurrence; D012720:Severity of Illness Index
D000928:Antidepressive Agents