# Lifetime Mixed Depression and Childhood Trauma in Individuals With Bipolar Disorders

## TL;DR

The study finds that people with bipolar disorder who experience mixed depression have a higher history of childhood trauma, especially emotional abuse, compared to those without mixed depression and healthy controls.

## Contribution

This is the first study to investigate the specific relationship between lifetime childhood trauma and lifetime mixed depression in bipolar disorder patients.

## Key findings

- Bipolar disorder patients with mixed depression reported significantly higher childhood trauma scores than non-mixed depression patients and healthy controls.
- Emotional abuse was identified as a strong and independent predictor of lifetime mixed depression in bipolar disorder.
- Physical trauma was linked to bipolar depression in general, while physical neglect was more associated with non-mixed depression.

## Abstract

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.

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.

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.

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.

Significant outcomes○Individuals with bipolar disorders and lifetime mixed depression show a higher burden of childhood trauma compared with those with non‐mixed depression and healthy controls.○Emotional trauma, particularly emotional abuse, is specifically associated with mixed depressive presentations and independently predicts lifetime mixed depression.○Physical trauma represents a general vulnerability factor for bipolar depression irrespective of depressive phenotype, whereas physical neglect appears more closely related to non‐mixed depressive presentations.
Limitations○Due to the cross‐sectional study design, we identified associations between childhood trauma and lifetime depressive phenotypes in bipolar disorders, but causality cannot be established.○Childhood trauma was assessed retrospectively using a self‐report measure, which may be influenced by recall bias and subjective reinterpretation of early experiences.○The definition of mixed depression used was limited to depressive episodes, without considering mixed features emerging in other mood states.

Significant outcomes○Individuals with bipolar disorders and lifetime mixed depression show a higher burden of childhood trauma compared with those with non‐mixed depression and healthy controls.○Emotional trauma, particularly emotional abuse, is specifically associated with mixed depressive presentations and independently predicts lifetime mixed depression.○Physical trauma represents a general vulnerability factor for bipolar depression irrespective of depressive phenotype, whereas physical neglect appears more closely related to non‐mixed depressive presentations.

Individuals with bipolar disorders and lifetime mixed depression show a higher burden of childhood trauma compared with those with non‐mixed depression and healthy controls.

Emotional trauma, particularly emotional abuse, is specifically associated with mixed depressive presentations and independently predicts lifetime mixed depression.

Physical trauma represents a general vulnerability factor for bipolar depression irrespective of depressive phenotype, whereas physical neglect appears more closely related to non‐mixed depressive presentations.

Limitations○Due to the cross‐sectional study design, we identified associations between childhood trauma and lifetime depressive phenotypes in bipolar disorders, but causality cannot be established.○Childhood trauma was assessed retrospectively using a self‐report measure, which may be influenced by recall bias and subjective reinterpretation of early experiences.○The definition of mixed depression used was limited to depressive episodes, without considering mixed features emerging in other mood states.

Due to the cross‐sectional study design, we identified associations between childhood trauma and lifetime depressive phenotypes in bipolar disorders, but causality cannot be established.

Childhood trauma was assessed retrospectively using a self‐report measure, which may be influenced by recall bias and subjective reinterpretation of early experiences.

The definition of mixed depression used was limited to depressive episodes, without considering mixed features emerging in other mood states.