Personality disorders and the prediction of alcohol use outcomes for women: Dimensional versus categorical classification

The impending shift in the fifth edition of Diagnostic and Statistical Manual of Mental Disorders from categorical to a hybrid categorical-dimensional diagnosis scheme has generated considerable interest in the relative merits of these respective approaches. This is particularly true for the diagnostically complex category of personality disorders (PDs). The present study assessed whether categorical or dimensional measures better predicted alcohol consumption in a sample of 102 women enrolled in a clinical trial comparing individual cognitive behavioral therapy (CBT) to conjoint CBT for alcohol use disorders (AUDs). Linear regression was used to evaluate whether each PD diagnosis (categorical), or the number of PD symptoms endorsed per PD (dimensional) better predicted percent days drinking over the course of six months of treatment. PD criteria (dimensional) better predicted drinking for Paranoid, Borderline, and Obsessive-Compulsive PDs, while diagnosis (categorical) was a better predictor only for passive-aggressive PD. Both schemes predicted drinking outcomes for avoidant, dependent, and depressive PDs, and neither was predictive for narcissistic PD. These findings suggest that the addition of a dimensional approach for PDs potentially enhances the prediction of alcohol use outcomes.