The diagnosis constraint of acute stress disorder (ASD), consisting of testing individuals in the month following trauma exposure, limits research on the very early and initial stage of the disease. In this regard, this work aims to explore the cerebral mechanism of ASD in a population of fire-fighters before and after trauma exposure. Thirty-six healthy non-traumatized male fire-fighters were explored by an fMRI emotional face-matching task to evaluate the cerebral substrate of emotional recognition. During the two years of the follow-up, two subjects were traumatized, and thus retested, as were 10 non-traumatized subjects among the initial non-exposed ones. In comparison to non-exposed subjects, fire-fighters with ASD had enhanced amygdala, orbitofrontal, and dorsolateral prefrontal BOLD responses to fearful and angry faces (p < .05, FDR-corrected). These results shed new light on the cerebral mechanism associated with ASD. We observed for the first time the existence of an altered fear processing pathway in ASD that is mediated by amygdala and prefrontal cortex hyperactivity, which might be at the core of the disorder.
Keywords: Acute stress disorder; Amygdala; Dorsolateral prefrontal cortex; Emotion; Orbitofrontal cortex; fMRI.