Subthreshold symptoms of depression in preadolescent girls are stable and predictive of depressive disorders.

OBJECTIVE: Given the risk for adolescent depression in girls to lead to a chronic course of mental illness, prevention of initial onset could have a large impact on reducing chronicity. If symptoms of depression that emerge during childhood were stable and predictive of later depressive disorders and impairment, then secondary prevention of initial onset of depressive disorders would be possible.
METHOD: Drawing from the Pittsburgh Girls Study, an existing longitudinal study, 232 nine-year-old girls were recruited for the present study, half of whom screened high on a measure of depression at age 8 years. Girls were interviewed about depressive symptoms using a diagnostic interview at ages 9, 10, and 11 years. Caregivers and interviewers rated impairment in each year.
RESULTS: The stability coefficients for DSM-IV symptom counts for a 1- to 2-year interval were in the moderate range (i.e., intraclass coefficients of 0.40-0.59 for continuous symptom counts and Kendall tau-b coefficients of 0.34-0.39 for symptom level stability). Depressive disorders were also relatively stable at this age. Poverty moderated the stability, but race and pubertal stage did not. Among the girls who did not meet criteria for a depressive disorder at age 9 years, the odds of meeting criteria for depressive disorders and for demonstrating impairment at age 10 or 11 years increased by 1.9 and 1.7, respectively, for every increase in the number of depression symptoms.
CONCLUSIONS: Early-emerging symptoms of depression in girls are stable and predictive of depressive disorders and impairment. The results suggest that secondary prevention of depression in girls may be accomplished by targeting subthreshold symptoms manifest during childhood.