Abnormal myelin could be a mediator of childhood-trauma-induced depression: A quantitative synthetic MRI study
Junyan Wen1, Shuqiong Zheng2, Zhimin Chen1
1Department of Medical Imaging, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
Objectives:
Major depressive disorder (MDD) is a prevalent mental illness with unclear underlying pathophysiology that is often linked to childhood trauma. Emerging evidence suggests a potential association between myelin abnormalities and depression, highlighting the need for further understanding of these neurobiological connections in MDD patients. This study investigated the mediating role of abnormal myelin in the pathophysiology of MDD induced by childhood trauma via quantitative Synthetic Magnetic Resonance Imaging (SyMRI) technique.
Methods:
MDD patients and healthy controls underwent SyMRI scanning to assess myelin content, T1, T2 and proton density (PD) values in the brain. Statistical analyses compared these values between groups and correlated them with clinical symptom scores. Mediation analysis was used to determine the role of myelin content in the relationship between childhood trauma and clinical symptoms.
Results:
Thirty-five MDD patients (median age, 23[18-34] years, 7 men) and forty-nine healthy controls (median age, 24[21-35] years, 18 men) were included. Compared with healthy controls, MDD patients presented significantly lower myelin content (FDR-corrected p < 0.05; Cohen's d = -0.85 - -0.75) and higher PD values (FDR-corrected p < 0.05; Cohen's d = 0.71-0.94) in the left inferior frontal sulcus, left caudal area 45, left medial area 14, left rostral area 7, left lateral area 5, left ventral dysgranular and granular insula, and left nucleus accumbens. The T1 and T2 values were not significantly different (FDR-corrected p > 0.05). A lower myelin content was significantly correlated with higher depression and anxiety scores (p < 0.05; R = 0.1309-0.2550). A myelin reduction in the left lateral area 5 and left ventral dysgranular and granular insula mediated the association between childhood trauma and MDD symptoms (p < 0.05; β = 0.0643-0.0807).
Conclusion:
Our findings suggest that reduced myelin content in the left lateral area 5 and left ventral dysgranular and granular insula, due to childhood trauma, mediated 6.4% to 8.1% of the variance of MDD. However, the cross-sectional design limits causal inference, and the influence of comorbid anxiety was not controlled.
Insights
Childhood trauma is linked to major depressive disorder (MDD) through reduced myelin content in specific brain regions. This myelin reduction mediates the association between trauma and MDD symptoms, offering neurobiological insights.
Area of Science:
- Neuroimaging
- Psychiatry
- Neurobiology
Background:
- Major Depressive Disorder (MDD) is a common mental illness with poorly understood pathophysiology, often associated with childhood trauma.
- Emerging research suggests a link between myelin abnormalities and depression, necessitating further investigation into these neurobiological connections in MDD.
- Myelin, the protective sheath around nerve fibers, plays a crucial role in brain function, and its alterations may contribute to psychiatric disorders.
Purpose of the Study:
- To investigate the mediating role of abnormal myelin in the pathophysiology of MDD induced by childhood trauma.
- To utilize quantitative Synthetic Magnetic Resonance Imaging (SyMRI) to assess myelin content and related metrics in MDD patients and healthy controls.
- To explore the relationship between myelin abnormalities, childhood trauma, and clinical symptoms of depression and anxiety.
Main Methods:
- Quantitative SyMRI scans were performed on 35 MDD patients and 49 healthy controls to measure brain myelin content, T1, T2, and proton density (PD) values.
- Statistical analyses compared these neuroimaging metrics between groups and correlated them with clinical symptom scores.
- Mediation analysis was employed to determine if myelin content mediates the relationship between childhood trauma and MDD symptoms.
Main Results:
- MDD patients exhibited significantly lower myelin content and higher PD values in several left-sided brain regions, including the inferior frontal sulcus, area 45, area 14, area 7, area 5, insula, and nucleus accumbens, compared to controls.
- Reduced myelin content in specific areas (left lateral area 5 and left ventral dysgranular and granular insula) was found to mediate the association between childhood trauma and MDD symptoms.
- Lower myelin content significantly correlated with higher depression and anxiety symptom scores.
Conclusions:
- Reduced myelin content in the left lateral area 5 and left ventral dysgranular and granular insula, potentially stemming from childhood trauma, mediates a significant portion of MDD variance.
- The findings suggest myelin abnormalities as a key neurobiological mechanism linking childhood trauma to MDD.
- The study's cross-sectional design limits causal inference, and the impact of comorbid anxiety requires further investigation.
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