Evaluation of an Online Cognitive Behavioural Therapy, Mindfulness Meditation, and Yoga (CBT-MY) Intervention for Posttraumatic Stress Disorder: A Single Arm Clinical Trial with Psychometric and Psychophysiological Outcomes

Objective: The aim of this dissertation was to evaluate an online cognitive behavioural therapy intervention that combined mindfulness and yoga (CBT-MY) in the treatment of posttraumatic stress disorder (PTSD). A secondary objective was to explore objective measures of autonomic function among adults with PTSD. Methodology: This single-arm experimental trial was conducted at York University. A total of 22 adults with PTSD symptoms were recruited to complete an 8-week intervention consisting of weekly CBT-MY material and one hour of virtual, phone-based CBT counselling each week. Psychometric outcomes of PTSD, depression, anxiety, chronic pain, and mindfulness were collected a two time points (baseline, post-intervention). Objective measures of pupillometry and heart rate variability (HRV) were examined during a 25-minute protocol consisting of rest, a stress task, and guided meditation. Psychophysiology outcomes of PTSD participants were compared with cross-sectional data from a convenience cohort of 49 non-PTSD-affected control participants that completed the computer protocol at a single time point and did not receive the intervention. Results. Pre-post analyses revealed large reductions in PTSD symptom severity (d = 1.60), depression (d = 0.83), anxiety (d = 0.99), and increased mindfulness (d = 0.88). Linear mixed effects modelling revealed a significant main effect of time with reductions in peak pupil dilation (PPD) post-intervention (M = -.06, SE = .01, p = .001) but no significant change in pre-post HRV (p = .87). Significantly lower HRV in PTSD subjects was observed compared to non-PTSD participants (F1,65 = 14.54, p = .001, 2 = .10). Conclusion. 8-weeks of online CBT-MY with weekly phone-based counselling shows promise in the reduction of PTSD symptom severity and associated mental health outcomes beyond clinically meaningful ranges. Autonomic function was less clear and supported improved pupillometry response. Findings lend support for future randomized trials investigating integrated online CBT-MY treatment in reducing PTSD symptom severity.