Comparing four competing models of depressive symptomatology: a confirmatory factor analytic study of 986,647 U.S....

Few rigorous studies have examined the factor structure of major depression symptoms as assessed by current diagnostic systems. This study evaluated four competing models of depressive symptomatology among a large, heterogeneous sample of U.S. veterans.

To determine the best fitting model of major depressive symptoms among four competing models, this study conducted a series of confirmatory factor analyses on a national sample of 986,647 U.S. veterans.

A two-factor model first reported by Krause, Reed, and McArdle (2010) provided superior fit to symptom-level data compared to three other models. The optimal model consists of a somatic factor including anhedonia, sleep difficulties, fatigue, appetite changes, concentration difficulties, and psychomotor agitation; and a non-somatic factor including depressed mood, feelings of worthlessness, and thoughts of death. Factorial invariance testing found this model to be invariant by gender and major depression diagnosis.

A widely used self-report measure of depression was used and the sample consisted solely of veterans so further study is needed with clinician-administered measures and non-veteran samples.

Together, these findings support separating symptoms of major depression into somatic and non-somatic factors which may have clinical relevance, and help clarify debates about the factor structure of depressive symptoms.