Tonic immobility in a large community sample : Prevalence and association with PTSD symptoms

People can be paralyzed when facing threat. Such paralysis, or “peritraumatic tonic immobility” (TI), is important as it seems associated with later PTSD development. However, the prevalence of TI is not known. This study investigated its prevalence in a large representative sample as well as its association with PTSD. 4781 participants from the general population completed measures of peritraumatic TI, peritraumatic fear, trait anxiety, dissociative tendencies, behavioral inhibition, and PTSD symptoms. Extreme TI was rare in participants without PTSD (0.6% in those without trauma and 0.8% in those with trauma but without PTSD) but not in those with PTSD (7.6%). Moderate TI occurred more often (6.3% up to 17.7% in participants without and with PTSD respectively). In multivariate analyses TI, trait anxiety and dissociative tendencies predicted PTSD severity, with trait anxiety and TI being the most relevant predictors. These results stress the relevance of further exploration of TI responses