Long-term tract-specific white matter microstructural changes after acute stress

Linghui Meng,Tong Shan,Qiyong Gong,Kaiming Li

doi:10.1007/s11682-020-00380-w

Abstract

Acute stress has substantial impact on white matter microstructure of people exposed to trauma. Its long-term consequence and how the brain changes from the stress remain unclear. In this study, we address this issue via diffusion tensor imaging (DTI). Twenty-two trauma-exposed individuals who did not meet post-traumatic stress disorder (PTSD) diagnostic criteria were recruited from the most affected area of Wenchuan earthquake and scanned twice (within twenty-five days and two years after the quake, respectively). Their emotional distress was evaluated with the Self-Rating Anxiety/Depression Scales (SAS/SDS) at both scans. Automatic fiber quantification was used to examine brain microstructure alterations. Correlation analyses were also conducted to investigate relationships between brain microstructure changes and symptom improvement. A group of demographically matched healthy controls (N = 22) from another project were scanned once before the quake using the same imaging protocols as used with trauma-exposed non-PTSD (TENP) participants. Two years after the earthquake, TENP individuals exhibited significantly reduced FA in the parietal portion of left superior longitudinal fasciculus and high FA in the parietal portion of left corticospinal tract. Over the follow-up, increased FA of the left uncinate fasciculus and the left corticospinal tract with parallel reduction of SAS and SDS were observed in TENP. No significant association was found between brain microstructure changes and symptom improvement. These results indicate changes in WM microstructure integrity of TENP brains parallel with symptom improvement over time after acute stress. However, the change would be a long-term process without external intervention.

Highlights

Extreme traumatic events have significant adverse effects on more and more individuals around the world (Satcher et al 2007), 46.9% of which are acute (Benjet et al 2016)
Mean White matter (WM) measures over tracts No group difference in mean fractional anisotropy (FA) was identified between traumaexposed non-posttraumatic stress disorder (PTSD) people (TENP) and healthy controls (HC) for any of the 20 resultant fiber tracts from automatic fiber quantification (AFQ)
TENP individuals still demonstrated aberrant FA values in the parietal segments of superior longitudinal fasciculus (SLF) and corticospinal tract (CST) compared with HC, indicating that the affected WM microstructure integrity in TENP persisted after two years

Summary

Introduction

Extreme traumatic events (i.e., natural disaster, accident, physical or sex abuse, combat) have significant adverse effects on more and more individuals around the world (Satcher et al 2007), 46.9% of which are acute (Benjet et al 2016). A large group of trauma-exposed people will not develop into PTSD but may still exhibit some signs of anxiety and depressive symptoms in the aftermath of the trauma. Structural and functional changes have been found in TENP shortly after trauma (Chen et al 2013; Lui et al 2013, 2009), the long-term brain alteration after acute stress remains largely unknown. Investigation of this matter may provide important insights on the brain’s mechanisms of resilience from acute stress

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Conclusion