Predictors of comorbid obsessive-compulsive disorder and skin-picking disorder in trichotillomania.

BACKGROUND: Trichotillomania (TTM), obsessive-compulsive disorder (OCD), and skin-picking disorder (SPD) frequently occur together and share overlapping phenomenology, pathophysiology, and possible genetic underpinnings. This study sought to identify factors that predict OCD and SPD in hair pullers.
METHODS: Five hundred fifty-five adult female hair pullers were recruited from specialty clinics and assessed using standardized, semi-structured interviews and self-reports. Clinical predictors and multivariate models were evaluated using logistic regression modeling.
RESULTS: Hair pullers met criteria for OCD (18.9%), SPD (19.5%), or chronic skin picking (CSP) (5%), or both comorbid diagnoses, respectively. In the final multivariate model for OCD, family history of OCD and an eating disorder diagnosis were associated with an increased risk of OCD in TTM. A nail-biting diagnosis was associated with a decreased risk of OCD in TTM. In the final multivariate model for SPD/CSP, only family history of OCD was associated with an increased risk of SPD/CSP in TTM.
CONCLUSIONS: Identification of factors predicting OCD and SPD in TTM provides evidence for the relatedness of these disorders and supports their collective classification as obsessive-compulsive and related disorders (OCRDs) in DSM-5. The findings of this study further underscore the importance of assessing for comorbid OCRDs and family histories of OCRDs in clinical practice.