Nature and extent of Posttraumatic Stress Disorder (PTSD) symptoms presenting in an adult psychological therapies service
Noel, Penelope Jacqueline
Posttraumatic stress disorder (PTSD) is complex and no one theory can fully explain the development and maintenance of PTSD symptoms. In Scotland, where trauma focused care initiatives are being considered, little is known about the extent of trauma history and associated symptoms presenting in primary care services. Furthermore, subthreshold posttraumatic stress disorder (sPTSD) has recently been associated with clinically significant impairment. With PTSD symptoms often comorbid with other psychopathology such as depression, individuals potentially seek treatment for these symptoms rather than underlying trauma which therefore may go unrecognised. Studies on the effectiveness of psychological treatment for PTSD demonstrate reasonable efficacy for well developed interventions. However, up to half of individuals may not make significant clinical improvements and withdrawal rates are high. This suggests that current treatments are not acceptable to some individuals and may be ineffective for others. In light of such clinical challenges the aim of the thesis was to investigate the incidence and nature of trauma symptoms in an Adult Psychological Therapies Service. Firstly, a systematic review was conducted to appraise the current level of evidence for prevalence and impairment associated with sPTSD. Secondly, an empirical study was undertaken to review the prevalence of trauma history and symptoms in the service. This was followed by an investigation of the relationships between processes posited to underpin many forms psychological distress by a promising new treatment approach called Acceptance and Commitment Therapy (ACT). These include; cognitive fusion, experiential avoidance and valued action. A quantitative cross sectional design collecting self report questionnaire data was used and mixed statistical methodology employed. Results from the systematic review suggest that PTSD was associated with the most impairment, followed by sPTSD, then no PTSD. Subthreshold PTSD was reported to be as, or more prevalent than, PTSD. The results from the empirical study found 89 per cent reported exposure to one or more traumatic events, 51 per cent met PTSD screening criteria, whilst a further 7 per cent reached a sPTSD diagnostic cut-off. Trauma history was positively correlated with increased psychological distress at initial assessment. Cognitive fusion, experiential avoidance and valued action were all correlated with trauma symptom severity. Both cognitive fusion and experiential avoidance mediated the relationship between number of traumatic events and trauma symptom severity in a simple mediation model. However, multiple mediation analysis demonstrated that experiential avoidance, over and above cognitive fusion, explained 33 per cent of the variance. In addition, cognitive fusion and experiential avoidance jointly had a significant indirect effect on the relationship between trauma history and valued action. The implications of the findings and further directions are discussed.