Higher order dimensions in the DSM/ICD obsessive-compulsive and related disorders

Obsessive-compulsive spectrum disorders are rarely included in hierarchical dimensional models of psychopathology due to limited available data. The current study examined the higher order structure of the obsessive-compulsive and related disorders (OCRDs) in the DSM/ICD.

Measures of OCRD severity were administered in community (N = 1110) and clinical (N = 690) samples. Confirmatory factor analyses were used to determine the optimal structure of OCRD symptoms, and structural regression models to explore association with indicators from the internalizing, externalizing and thought disorder spectra.

In both samples, the data fit best with a correlated two-factor model comprised of a grooming dimension (with loadings from hair pulling, skin picking and nail biting/picking disorders) and a compulsivity dimension (with loadings from obsessive-compulsive, hoarding, body dysmorphic, olfactory reference, and illness anxiety disorders). A three-factor model which included body preoccupation factor (body dysmorphic, olfactory reference, and illness anxiety disorders) was not viable due to out of bounds correlations with compulsivity (obsessive-compulsive and hoarding disorders). The broad compulsivity factor, but not the grooming factor, had robust associations with indicators of internalizing and thought disorder spectrum. Both factors had small and inconsistent associations with alcohol and substance use.

The findings suggest that the higher order structure of OCRDs may be best represented by separable compulsivity and grooming dimensions. Future research is needed to examine the scope of these dimensions, and their placement within the meta structure of psychopathology.