Comorbidity and heterogeneity: Two challenges for personality pathology research

We critique the general state of methodological rigor in contemporary personality pathology research, focusing on challenges in study design, assessment, and data analysis resulting from two pervasive problems: comorbidity and heterogeneity. To inform our understanding of this literature, we examined every article published in the two main specialty journals for personality pathology research-Personality Disorders: Theory, Research, and Treatment and the Journal of Personality Disorders-in the 18-month period from January 2020 to June 2021 (a total of 23 issues and 197 articles). Our review of this database indicated that only three forms of personality pathology have generated substantial attention in the recent literature: borderline personality disorder (featured in 93 articles), psychopathy/antisocial personality disorder (39 articles), and narcissism/narcissistic personality disorder (28 articles), so we highlight them in our review. We discuss comorbidity-related problems that arise from group-based designs and recommend instead that researchers assess multiple forms of psychopathology as continuous dimensions. We offer separate recommendations for addressing heterogeneity in diagnosis- versus trait-based studies. For the former, we recommend that researchers (a) use measures that permit criterion-level analyses and (b) routinely report criterion-level results. For the latter, we emphasize the importance of examining specific traits when measures are known to be highly heterogeneous/multidimensional. Finally, we encourage researchers to work toward a truly comprehensive trait dimensional model of personality pathology. We suggest that this might include expanding the current alternative model of personality disorders to include additional content related to borderline features, psychopathy, and narcissism. (PsycInfo Database Record (c) 2023 APA, all rights reserved).