Lifetime Mixed Depression and Childhood Trauma in Individuals With Bipolar Disorders

Background and Aims: Mixed Depression (MxD), characterized by the co-occurrence of depressive and excitatory symptoms, is a prevalent yet often underdiagnosed presentation in bipolar disorders (BD), with significant implications for prognosis and treatment. Childhood trauma is a key environmental risk factor associated with a more severe course of BD, as it influences its onset, progression, and clinical presentation. To date, no studies have specifically investigated the relationship between lifetime childhood trauma and lifetime MxD in individuals with BD. The aim of our study was to address this gap in a large and well-characterized sample of patients with BD type I and type II. Methods: A total of 376 individuals, 220 euthymic outpatients with BD (MxD = 100, non-MxD = 120) and 156 healthy controls (HC), were enrolled. Childhood trauma was assessed using the Childhood Trauma Questionnaire (CTQ). Lifetime MxD was identified according to the Koukopoulos criteria. The relationship between childhood trauma and MxD was evaluated using two different multivariate models. Results: The first model (Wilks' Lambda = 0.834, p < 0.001) revealed that BD patients with lifetime MxD reported significantly higher CTQ total scores compared to both non-MxD (p = 0.029) and HC (p < 0.001). When examining childhood trauma subtypes, BD patients with MxD reported significantly higher emotional abuse scores than those without MxD (p < 0.001). Furthermore, compared to HC, the MxD group showed significantly elevated scores in emotional abuse, emotional neglect, and physical abuse (all p < 0.001). The non-MxD group scored higher than HC on physical abuse (p = 0.008) and physical neglect (p < 0.001). Regression analyses confirmed specifically emotional abuse as a significant predictor of lifetime MxD. Conclusions: The findings demonstrate a strong association between childhood trauma, particularly emotional abuse, and lifetime MxD. These results underscore the significance of childhood trauma as a key predictor of clinical outcomes in BD.