| The primary purpose of this dissertation research was to identify emerging psychological and contextual variables that contribute to the development of acute stress disorder (ASD) and posttraumatic stress disorder (PTSD) following a motor vehicle crash (MVC) and to explore their linkages to neurobiological tests of autonomic arousal and hypothalamic-pituitary-adrenal (HPA) axis activity. An integrative, prospective, repeated measures, correlational design was used. Meeting criteria for the ASD group was associated with increased symptom frequency and intensity on all PTSD and Impact of Event Scale (IES) subscales. Hyperarousal symptoms were the most frequently experienced of the three symptom clusters that must be present for a diagnosis of ASD or PTSD. High hyperarousal levels were associated with increased anxiety symptoms, postraumatic dissociation, and use of coping strategies at both two- and six-weeks post-MVC and with lower daytime cortisol levels. High hyperarousal levels two weeks postMVC were strongly predictive of PTSD at six weeks post-MVC. The expected associations between the sympathetic-adrenal medullary (SAM) and HPA systems and the SAM system and PTSD were not found. Together, the findings underscore the severity of stress-related symptoms that MVCs can evoke in individuals and the complexity of interactions among components of stress response systems.;A secondary repeated measures study assessed acoustic startle reactivity in healthy women during their mid-luteal and mid-follicular menstrual cycles. No significant menstrual phase effects on startle amplitude, habituation, latency, latency facilitation or PPI were found. Women showed significant habituation and greatest PPI at the shortest prepulse interstimulus interval in both phases. These findings were integrated into the discussion of the startle data for the pre-menopausal female participants in the MVC study. |
