Abstract
In search of the neural basis of severe trauma exposure and post-traumatic stress disorder (PTSD), a multitude of cross-sectional studies have been conducted, most of them pointing at structural deficits in the hippocampus and medial prefrontal cortex including the anterior cingulate cortex (ACC) and ventromedial prefrontal cortex (vmPFC). Since cross-sectional studies are silent to causality, the core question remains: which brain structural alterations constitute a risk factor for disease and therewith precede the stressor, and which brain regions may undergo alterations as a consequence of exposure to the stressor. We assessed 121 soldiers before and after deployment to regions of war and 40 soldiers as controls, who were not deployed. Analysis using voxel-based morphometry revealed volumetric reductions in the ACC, vmPFC (region of interest analysis, effect does not survive conservative multiple test correction) and in bilateral thalamus (whole-brain analysis) in the deployment group. Remarkably, the ACC and vmPFC volume decrease was not limited to the period of deployment, but continued over the following 6 months after deployment. Volumetric reductions did not correlate with increases in PTSD symptoms. The volume decreases in medial prefrontal cortex and thalamus seem to be driven by trauma exposure rather than a vulnerability factor for PTSD. However, data indicate that the volume decrease in medial prefrontal cortex surpasses the time period of deployment. This may hint at an initiated pathobiological process below a symptom threshold, potentially paving the way to future mental health problems.
Highlights
Stress is an ubiquitous phenomenon in our daily lives and its negative impact on mental and physical health has long been recognized1
Since we were focusing on withinsubject changes, we did not control for covariates such as sex and total intracranial volume (TIV), but for age, because we found a significant group difference at Baseline (Table 1)
The most frequently reported events were: having experienced hostility by civilians, having seen corpses or parts of dead bodies, having seen destroyed houses and towns, having seen sick or wounded women or children, whom the soldiers could not help, and explosions in the immediate vicinity caused by improvised explosive devices (IED)
Summary
Stress is an ubiquitous phenomenon in our daily lives and its negative impact on mental and physical health has long been recognized. Effects of extremely stressful life events such as the experience of acts of terrorism, natural disaster or military combat are difficult to study, since these events are rare and less predictable. Individuals respond very differently to exposure to traumatic events, with some showing resilience and others developing psychiatric diseases such as post-traumatic stress disorder (PTSD) or depression. In search of the neural basis of trauma exposure and/or PTSD a multitude of cross-sectional studies have been. Follow-up I Baseline Mean (SD) Mean (SD).
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