Predisposing risk factors for PTSD: Brain biomarkers

Post-traumatic stress disorder (PTSD) diagnosis entails exposure to an external stressful event. Regarding such event as a reference point for disease onset represents a unique opportunity to investigate which, if any, of the neural abnormalities that characterize PTSD constitute a predisposing (pre-exposure) risk factor. This chapter reviews findings from four novel research strategies in PTSD neuroimaging, including prospective, environmental, twin, and genetic studies together suggesting that abnormal structure, function, and connectivity within the amygdala and dorsal anterior cingulate cortex circuitry may represent predisposing neural abnormalities that existed prior to exposure to trauma and increased the likelihood to develop PTSD following it. Considering the emotional–cognitive functions of this neural circuit, we further postulate that exaggerated fear generation and dysfunctional regulation of fear may represent predisposing behavioral phenotypes leading to PTSD symptom cluster of hyperarousal.