Mapping emotional disorders at the finest level: Convergent validity and joint structure based on alternative measures

Background Traditional categorization of emotional disorders suffers from within-disorder heterogeneity and excessive comorbidity. Quantitative nosology instead proposes grouping homogenous components of these disorders within a higher order internalizing dimension. However, the precise number, composition, and hierarchical structure of these components remains unclear and varies based on assessment tools. Methods The present study jointly examined two assessment systems with the broadest coverage of homogeneous emotional disorder components—the revised Interview for Mood and Anxiety Symptoms (IMAS-R) and the self-report-based expanded version of the Inventory of Depression and Anxiety Symptoms (IDAS-II)—to map their convergent and discriminant validity and joint structure in outpatient (N = 426) and treated student (N = 306) samples. Results Results identified 33 non-redundant components of emotional disorders. Most demonstrated strong convergent and discriminant validity between these two instruments. However, the IMAS-R provided more detailed and differentiated characterization of the content subsumed within three IDAS-II scales, and seven of the 33 components were unique to one measure or the other. Joint analysis of scales from both measures supported a four factor (i.e., distress, fear, OCD, mania) mid-level structure of emotional disorders. Conclusions Using multiple measures, methods, and samples, the present study provided evidence for the validity of core lower order components of the internalizing dimension and suggested they cluster into as many as four distinct factors reflecting distress, fear, OCD, and mania.