Cognitive Change in Individuals with Posttraumatic Stress Disorder

Abstract

Posttraumatic stress disorder (PTSD) is a prevalent psychiatric condition in Canada, with a lifetime prevalence of 9.2% among Canadian civilians and 12.7% among Canadian veterans. While there exists a substantial body of research delving into the cognitive abilities of younger adults affected by PTSD, less is known about the cognitive profile of middle-aged and older adults with symptoms of PTSD. Often built on cross-sectional designs with relatively small sample sizes, and frequently utilizing group analysis, these studies might have restricted capacity to unveil distinct cognitive profiles within people exhibiting symptoms of PTSD symptoms.

In addition, recent research indicates that people with PTSD face an elevated risk of developing dementia, with subtle cognitive deficits potentially serving as precursors to cognitive decline leading to dementia. Nonetheless, specific lifestyle elements, such as education, physical activity, social support, and mental engagement, have demonstrated their potential to alleviate cognitive decline in various conditions. These factors, termed cognitive reserve factors, remain scarcely investigated in relation to their influence on cognition among individuals with PTSD.

The dissertation focuses on three main goals: 1) measuring cognitive changes related to PTSD in a diverse sample of middle-aged and older adults, including veterans; 2) assessing cognitive decline over time between those with and without symptoms of PTSD; 3) investigating if certain lifestyle factors can serve as cognitive reserve mechanisms to reduce cognitive decline over time.

Using baseline data from the Canadian Longitudinal Study on Aging, Study 1 examined neuropsychological performance in a large group of middle-aged to older adults with PTSD symptoms. The study assessed impairment rates (performance scores 1.5 or more standard deviations below the mean) and also explored if a cognitive reserve factor (social support) could mitigate cognitive decline in both the PTSD and comparison groups, laying the groundwork for Study 2.

Study 2 aimed to assess the three-year longitudinal neuropsychological performance of middle-aged to older adults with PTSD symptoms. Expanding on Study 1, it investigated more cognitive reserve factors like physical activity, cognitive stimulation, education, social participation, and social support. The goal was to determine if these factors could improve neurocognitive test performance and if benefits were similar for the PTSD and comparison groups.

Given the unique health and well-being characteristics among Canadian veterans, especially their vulnerability to PTSD, Study 3 aimed to explore the cognitive differences between veterans and non-veterans with PTSD. Combining Study 1 and Study 2 objectives, it assessed the longitudinal neuropsychological performance of veterans with PTSD over three years. The study also assessed if a larger subset of veterans experienced clinically significant decline compared to civilians with PTSD.

The results indicated that a subset of people within the PTSD group initially showed low performance on tasks involving executive functioning. These individuals also showed significant decline in executive functioning tasks during the FU1 assessment. Intriguingly, veterans' cognitive profiles within the PTSD group remained similar to non-veterans over three years after accounting for TBI. Regarding cognitive reserve, the findings of both Study 1 and Study 2 imply that cognitive reserve factors might have a stronger impact on modifying cognitive processes in individuals without PTSD compared to those with PTSD.