Mixed anxiety depression: Taxometric exploration of the validity of a diagnostic category in youth

Background: Mixed anxiety depression (MAD) is a provisional diagnosis in the DSM-IV. This study determined whether MAD represents a discrete category thereby evaluating the validity of MAD as a diagnostic entity. Methods: Taxometric analyses and mixture modeling were used to discern whether MAD indicators constitute a distinct psychopathological category (i.e., a taxon) in a large school-based sample of adolescents (N = 706). Results: Each taxometric procedure (MAXCOV, MAMBAC) identified a taxon with a prevalence of 13% ± 2%. A non-taxometric procedure (multivariate mixture modeling) also supported the existence of a taxon with a prevalence of 12%. Bootstrapping procedures were used to construct a measure of MAD (i.e., MAD-T). Scale construction suggested that MAD may be best represented by 12 criteria that largely overlap with the DSM-IV, though some modifications were suggested. Examination of the construct validity of the MAD taxon indicated that it is associated mood and anxiety symptoms. Taxon membership was predictive of the development of mood and anxiety disorders over a 14-month longitudinal follow-up. Limitations: This category should be studied in other populations including adult samples. Conclusions: MAD appears to be a viable diagnostic category for youth though it is recommended that future revisions of the DSM emphasize somewhat different criteria for this diagnosis.