The relation between depressive symptoms and borderline personality disorder features over time in dysthymic disorder

Dysthymic Disorder (DD) and Borderline Personality Disorder (BPD) frequently co-occur. To understand this association better, we tested four competing models of the relationship between depressive and BPD symptoms over time in DD: (a) no association between depression and BPD over time; (b) contemporaneous direct effects in which BPD features and depressive symptoms influence one another over a relatively short time period; (c) lagged direct effects in which one condition influences the other condition over a longer period; and (d) a fixed common factor underlies both depression and BPD, along with influences that are unique to each condition. We assessed 84 outpatients with DD three times over 5 years using semistructured interviews. Data were analyzed using structural equation modeling techniques. The fixed common factor model was the best fitting of the models, providing an excellent fit to the data. These results suggest that depressive symptoms and BPD features in DD arise from partially overlapping processes.