Assessing physiological sensitivity in post-traumatic stress disorder

• Main Author: McKinnon, Aimee
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2017
• Subjects: Physiology; Post traumatic stress disorder

People who have endured horrific events often bear predictable psychological harm. The symptoms of this harm can persist to produce a recognised clinical syndrome, Post-Traumatic Stress Disorder (PTSD). The lived reality of PTSD is a condition in which sufferers experience unbearable emotional reactions to traumatic reminders and exist in a persistent state of fear. Although the psychiatric and psychological construct of PTSD has been hotly contested, research and clinical opinion seem to converge around a state of enhanced sensitivity to threat, underpinned by chronic physiological hyper-arousal. This thesis has been concerned with the development of assessment measures that are sensitive to physiological hyper-arousal, including pupillometry and visual contrast sensitivity. In three experiments, a sample of 73 participants recruited from military, addiction and homelessness charity services were assessed for PTSD symptomology with the Clinician Administered PTSD Scale for DSM-V, and the self-report Impact of Event Scale-Revised. During passive viewing of emotive images, individuals with PTSD showed pupil responses that were influenced more by emotive stimuli than controls, and showed a reduced constriction of the pupil to light; revealing altered states of arousal. Due to methodological differences, a task assessing pupil responses to emotive sound clips failed to replicate this result. The assessment of visual contrast sensitivity revealed the heterogeneous nature of PTSD. Multi-dimensional assessment of symptom subscales showed that higher levels of re-experiencing symptoms were related to heightened visual sensitivity, but avoidant symptoms were related to lower sensitivity. Overall, the assessment of psychophysiological responses in PTSD demonstrated the utility of pupillometry for the assessment of PTSD, contributed to the literature on the regulation of the autonomic nervous system in PTSD, and highlighted the diversity of the clinical construct due to opposing effects of the symptom subscales.