The Structure of Personality Disorders within a Depressed Sample: Implications for Personalizing Treatment

Personality disorders (PDs) and major depressive disorder (MDD) are both significant public health burdens. They are frequently comorbid, and this comorbidity predicts poorer treatment outcomes and lower maintenance of treatment effects. Although there is growing consensus on the structure of personality pathology in non-depressed individuals, there is limited research on the structure of personality pathology in individuals experiencing MDD.

As part of the Predictors of Remission in Depression to Individual and Combined Treatment (PReDICT) randomized controlled trial, 192 treatment-naïve subjects meeting DSM-IV-TR criteria for MDD completed the International Personality Disorder Examination (IPDE). Using this sample, a principal components analysis explored the factor structure of the IPDE.

A three-factor model comprised three factors labeled "NADA" (Negative Affectivity, Disinhibition, and Antagnoism)," "Social Anxiety," and "Antisociality." Factor intercorrelations were small-to-moderate, and the sum score of the three factors was highly correlated (r = .94) with the total IPDE score.

Personality pathology was assessed with one instrument, and sample size was smaller than ideal for factor analytic research. \.

Consistent with prior factor-analytic findings, a three-factor solution provided the most clinically and theoretically useful model. This finding lends support for the personality disorders retained in DSM-5 and some support for a model of personality pathology aligned with the personality traits found in the leading nonclinical models of personality. The obtained factors are potential moderators of clinical interventions and may serve as an avenue to personalizing treatments.