Covariation of the anxious-depressed syndrome during adolescence: separating fact from artifact.

Nosological (symptom overlap) and methodological (informant) artifact in the covariation of an empirically derived syndrome of anxious-depressed symptoms with 7 other syndromes of emotional and behavior problems was examined in reports by parents, teachers, and adolescents on a nationally representative sample of 908 adolescents. Although minor symptom overlap was observed and the effects of informant were significant, the anxious-depressed syndrome covaried significantly with all other syndromes after controlling for these effects. Indices of covariation controlling for informant effects were all significant and ranged for all syndromes except for delinquent behavior from .619 to .681, reflecting significant covariation of the anxious-depressed syndrome with both externalizing and internalizing syndromes. Covariation of the anxious-depressed syndrome and delinquent behavior was .470. Implications for research on the comorbidity-covariation of depressive syndromes during childhood and adolescence are highlighted.