Peritraumatic tonic immobility is associated with posttraumatic stress symptoms in undergraduate Brazilian students

objective: tonic immobility is a defensive reaction occurring under extreme life threats. patients with posttraumatic stress disorder (ptsd) reporting peritraumatic tonic immobility show the most severe symptoms and a poorer response to treatment. this study investigated the predictive falue of tonic immobility for posttraumatic stress symptoms in a non-clinical sample. methods: one hundred and ninety-eight college students exposed to various life threatening events were selected to participate. the posttraumatic stress disorder checklist - civilian version (pcl-c) and tonic immobility questions were used. linear regression models were fitted to investigate the association between peritraumatic tonic immobility and pcl-c scores. peritraumatic dissociation, peritraumatic panic reactions, negative affect, gender, type of trauma, and time since trauma were considered as confounding variables. results: we found significant association between peritraumatic tonic immobility and ptsd symptoms in a non-clinical sample exposed to various traumas, even after regression controlled for confounding variables (β = 1.99, p = 0.017). conclusions: this automatic reaction under extreme life threatening stress, although adaptive for defense, may have pathological consequences as implied by its association with ptsd symptoms.