Clinical Heterogeneity of Major Depressive Disorder: The Role of Trauma, Dissociation, and Sleep

Background: Major depressive disorder (MDD) is a common mental disorder characterized by a wide range of symptoms and a substantial contribution to global disease burden. Our study aimed to examine the relationships between childhood trauma, sleep quality, dissociative symptoms, posttraumatic growth, and suicidality in patients diagnosed with MDD. Methods: Our sample consisted of 115 patients with MDD and 84 healthy controls. Participants were administered the Hamilton Depression Rating Scale (HDRS), Beck Scale for Suicidal Ideation (BSSI), Pittsburgh Sleep Quality Index (PSQI), Childhood Trauma Questionnaire (CTQ-33), Dissociative Experiences Scale (DES), and Posttraumatic Growth Inventory (PTGI). Group differences were analyzed, and associations among variables within the MDD group were examined using correlation and mediation analyses. Results: Compared to healthy controls, patients with MDD had significantly higher scores on all scales except the PTGI (p < 0.001 for each). Within the MDD group, individuals with a history of suicide attempts had significantly higher CTQ total scores, physical and sexual abuse subscale scores, and DES scores than those without previous attempts. Additionally, dissociative experiences had a partial mediating role in the relationship between depression severity and suicidal ideation, as well as in the relationship between childhood traumas and sleep quality. Conclusions: The findings highlight the clinical relevance of dissociative experiences and sleep disturbances in the heterogeneous presentation of MDD and their association with illness severity and suicidality. In the follow-up and treatment process of patients with MDD, risk and protective factors should be evaluated together, and individualized treatment programs should be targeted.