biologicalpsychiatry etiology fysiologischeaspecten névrosespost-traumatiques pathophysiology physiologischepsychiatrie physiologischepsychologie physiopathologie physiopathology post-traumatic post-traumaticstressdisorder posttraumatischesstresssyndrom posttraumatischestressstoornis psychiatriebiologique psychobiologie psychobiology riskfactors stressdisorders