Background: Factor-analytic studies have found that depressive, bipolar, post-traumatic, obsessive-compulsive, and anxiety disorders - jointly referred to as the emotional disorders - form an internalizing spectrum that includes distress and fear subfactors. However, placement of some disorders is uncertain. Also, prior research analysed dichotomous interview-based diagnoses or dimensional self-report measures. We investigated this structure using a third-generation measure - the Interview for Mood and Anxiety Symptoms (IMAS) - that combines strengths of a clinical interview with dimensional assessment.
Method: The interview was administered to 385 students and 288 psychiatric out-patients. Participants were reinterviewed 2 months later.
Results: Exploratory and confirmatory factor analyses identified three factors: distress (depression, generalized anxiety, post-traumatic stress, irritability, and panic syndrome); fear (social anxiety, agoraphobia, specific phobia, and obsessive-compulsive); and bipolar (mania and obsessive-compulsive). The structure was consistent over time and across samples, except that panic and agoraphobia had higher factor loadings in patients. Longitudinal analyses revealed high temporal stability of the factors (test-retest r = 0.72 to 0.87), but also substantial disorder-specific stability.
Conclusions: This investigation - which bridges diagnostic and self-report studies - found three subfactors of internalizing psychopathology. It provided support for a new subfactor, clarified the placement of obsessive-compulsive and bipolar disorders, and demonstrated that this model generalizes across populations. The accumulating research suggests the need to recognize formally the close links among the emotional disorders, as well as empirical clusters within this spectrum. The IMAS demonstrated strong psychometric properties and can be useful for various research and clinical applications by providing dimensional, interview-based assessment of the emotional disorders.
Keywords: nosology.