Abstract
Most people are exposed to at least one traumatic event during the course of their lives, but large numbers of people do not develop posttraumatic stress disorders. Although previous studies have shown that repeated and chronic stress change the brain’s structure and function, few studies have focused on the long-term effects of acute stressful exposure in a nonclinical sample, especially the morphology and functional connectivity changes in brain regions implicated in emotional reactivity and emotion regulation. Forty-one months after the 5/12 Wenchuan earthquake, we investigated the effects of trauma exposure on the structure and functional connectivity of the brains of trauma-exposed healthy individuals compared with healthy controls matched for age, sex, and education. We then used machine-learning algorithms with the brain structural features to distinguish between the two groups at an individual level. In the trauma-exposed healthy individuals, our results showed greater gray matter density in prefrontal-limbic brain systems, including the dorsal anterior cingulate cortex, medial prefrontal cortex, amygdala and hippocampus, than in the controls. Further analysis showed stronger amygdala-hippocampus functional connectivity in the trauma-exposed healthy compared to the controls. Our findings revealed that survival of traumatic experiences, without developing PTSD, was associated with greater gray matter density in the prefrontal-limbic systems related to emotional regulation.
Highlights
Trauma exposure is common and could increase lifetime vulnerability to mental health problems when individuals encounter stress or adversity, especially the most traumatic events, such as a massive earthquake, terrorism or war [1,2,3]
We found that resilient trauma-exposed survivors showed greater gray matter density in prefrontal-limbic brain systems and lower gray matter density in the frontoparietal association cortex than controls
Resting-state functional connectivtiy analysis found that resilient trauma-exposed survivors showed strengthened functional connectivity between the amygdala and hippocampus compared to controls
Summary
Trauma exposure is common and could increase lifetime vulnerability to mental health problems when individuals encounter stress or adversity, especially the most traumatic events, such as a massive earthquake, terrorism or war [1,2,3]. Previous studies have indicated that trauma exposure could impact brain function and structure in nonclinical individuals [10,11,12], few studies have focused on the long-term effects of trauma exposure in a PLOS ONE | DOI:10.1371/journal.pone.0168315. Prefrontal-Limbic Systems Associated with Trauma Exposed nonclinical sample. It is not yet clear how the long-term effects of trauma exposure cause the change of brain structure and function associated with emotion and memory processing in trauma-exposed individuals. The changes in brain structure and functions might help us understand the neural mechanisms underlying both vulnerable and resilient individuals in this nonclinical sample
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