Microstructural alterations in gray matter after acute stress

Structural and functional changes in stress-related gray matter (GM) regions have been found in trauma-exposed individuals. However, the nature of underlying microstructural abnormalities in traumatized individuals is unclear. In this study, thirty-two motor vehicle accident (MVA) survivors and 31 nonexposed controls were recruited. MVA survivors were scanned and received trauma-specific clinical assessments within 7 days of their accident. Mean diffusivity (MD), fractional anisotropy (FA) and GM volume (GMV) were measured as indicators of GM structural changes in the medial orbitofrontal cortex (mOFC), amygdala, hippocampus, insula and anterior cingulate cortex (ACC) bilaterally. Correlation analyses were performed to explore the association between the resultant GM structure and anxiety symptoms. Significantly lower fractional anisotropy (FA) in the mOFC and ACC was detected in the MVA group. No difference was found in MD and GMV. No structural measures showed associations with anxiety symptoms. MVA survivors showed GM microstructure alterations shortly after acute stress. These findings contribute to a better understanding of alterations in GM structure occurring shortly after acute stress that manifest far earlier in posttraumatic responses.