The authors discuss, from the evolutionary concept, how flight and fight responses and tonic immobility can lead to a new understanding of posttraumatic stress disorder. Through the analysis of symptom clusters (revivals, avoidance and hyperexcitation), neurobiological and evolutionary findings are correlated. The current discoveries on posttraumatic stress disorder genetics are summarized and analyzed in this evolutionary perspective, using concepts to understand the gene-environment interaction, such as epigenetic. The proposal is that the research of susceptibility factors in posttraumatic stress disorder must be investigated from the factorial point of view, where their interactions increase the risk of developing the disorder, preventing a unique search of the cause of this disorder. The research of candidate genes in posttraumatic stress disorder must take into consideration all the systems associated with processes of stress response, such as the hypothalamus-pituitary-adrenal and sympathetic axes, mechanisms of learning, formation and extinguishing of declarative memories, neurogenesis and apoptosis, which involve many systems of neurotransmitters, neuropeptides and neurohormones.
Evolution; genetics; posttraumatic stress disorders; neurobiology