Comorbid personality disorders among patients with depression

Purpose: To investigate the personality disorders (PDs) diagnosed in patients with depressive disorders. Material and methods: This study included a cross-sectional analysis, and was an extension of the Thai Study of Affective Disorder (THAISAD) project. Eighty-five outpatients with depressive disorders were interviewed using the Mini International Neuropsychiatric Inventory to assess for depression, in accordance with the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision and using the Thai version of the Structured Clinical Interview for PDs to assess for PD. Results: Seventy-seven percent of the patients had at least one PD, 40% had one PD and 60% had two or more PDs (mixed cluster). The most common PDs found were borderline PD (20%) and obsessive-compulsive PD (10.6%), while the occurrence of avoidant PD was low when compared to the findings of previous, related studies. Among the mixed cluster, cluster A combined with cluster C was the common mix. Both dysthymic disorder and double depression were found to have a higher proportion of PDs than major depressive disorder (85.7% versus 76.1%). Dependent PD was found to be less common in this study than in previous studies, including those carried out in Asia. Conclusion: The prevalence of PDs among those with depressive disorder varied, and only borderline PD seems to be consistently high within and across cultures. Mixed cluster plays a prominent role in depression, so more attention should be paid to patients in this category.