The structure of anxiety and depression in a normative sample of younger and older Australian adolescents.

It has been reported that depression and anxiety have overlapping symptoms and are conceptually interrelated. One of the most prominent theoretical developments that explain this association is Clark and Watson's tripartite model (Journal of Abnormal Psychology, 100:316-336, 1991) that posits these two disorders and negative emotions share a latent component of negative affect (NA). The current study had two aims, (a) to compare a tripartite factor structure against competing models by Confirmatory Factor Analysis (CFA) of the Depression Anxiety and Stress Scales (DASS-21) (Lovibond and Lovibond 1995), and (b) explore the psychometric properties of the DASS-21. The DASS-21 was completed by a representative sample of 4039 young Australians, aged 12-18 years, as part of the South Australian Youth Mental Health Survey (SAYMHS), South Australia, Australia. The best fitting model for the data consisted of anhedonic depression, physiological hyperarousal, and general NA. The psychometric properties of the DASS-21 were excellent with a stable and interpretable factor structure and good internal consistency. The results of the current study suggest that the theoretical tripartite structure of depression and anxiety is robust and applicable among Australian youth. The diagnostic, clinical and theoretical implications of these findings are discussed.