Third, there need to be at least

three avoidance symptoms, which can include active avoidance of thoughts, feelings, or reminders of the trauma, inability to recall some aspect of the trauma, withdrawal from others, or emotional numbing. Fourth, one must suffer marked arousal, which can include insomnia, irritability, difficulty concentrating, hypervigilence, or heightened startle response. These symptoms must cause marked impairment to one’s functioning, and can only be diagnosed when they are present at least 1 month after the trauma. DSM.-IV Inhibitors,research,lifescience,medical also introduced a new diagnosis, acute stress disorder (ASD), to describe acute trauma reactions that occur in the initial month following a trauma. As PTSD is only diagnosed 1 month after trauma, it was decided that there was a need to fill the nosological gap between the traumatic event and PTSD, in part to

facilitate diagnosis and access to health care. A second major goal of the ASD diagnosis was to describe acute stress responses that precede longer-term PTSD, and therefore could be used to Inhibitors,research,lifescience,medical identify people who were at high risk for find protocol subsequent disorder and could benefit from early intervention. ASD is conceptually similar to PTSD and shares many of the Inhibitors,research,lifescience,medical same symptoms.5 A key difference between ASD and PTSD is the former’s emphasis on dissociative symptoms. Specifically, ASD requires the individual to experience at least three of the following: emotional numbing, reduced awareness of one’s surroundings, derealization, depersonalization, and dissociative amnesia. These symptoms may occur either Inhibitors,research,lifescience,medical at the time of the trauma or during the subsequent month. The dissociative symptoms were included in ASD on the premise that dissociative responses following trauma are predictive of subsequent PTSD, presumably because they limit emotional processing of the traumatic experience.5 Support for the inclusion of dissociative symptoms in the ASD diagnosis to predict Inhibitors,research,lifescience,medical subsequent PTSD came from evidence demonstrating

an association between peritraumatic dissociation and subsequent levels of PTSD, a finding that has been to replicated across several longitudinal studies.6-10 Across many longitudinal studies, the ASD diagnosis has been shown to be a flawed predictor of subsecpent PTSD.11 Nonetheless, ASD is being retained in DSM-5 as a descriptor of acute stress reactions.12 Differential diagnosis A key issue in this discussion is the overlap between symptoms accompanying each condition. In terms of the dissociative symptoms often observed in PTSD, and especially in the acute phase in ASD, there is much evidence that TBI can result in emotional numbing, derealization, reduced awareness of surroundings, depersonalization, and amnesia.13-15 The issue of amnesia is particularly important in cases of TBI and PTSD because of the difficulty in differentiating between organic and psychogenic amnesia.