Apolipoprotein E and Cognitive Impairment in PTSD: Assessing Genetic Risks and Protections

Abstract

This study bridges gaps in the Posttraumatic Stress Disorder (PTSD) literature by providing a rigorous evaluation of the relationships between trauma exposure, PTSD symptoms, Apolipoprotein E (ApoE), and cognitive functioning. A total of 932 U.S. veterans (N=643 males) completed diagnostic interviews of mental health, a cognitive screener, self-reports of PTSD symptom severity and exposure to traumatic events, and blood tests to collect genetic information. Analysis demonstrated that veterans with PTSD perform worse than those without on the Montreal Cognitive Assessment (MoCA), regardless of comorbid depression, and that current PTSD symptoms and Pre-deployment exposure to potentially traumatic events are associated with lower performance on MoCA. Interestingly, veterans with PTSD and a comorbid depressive disorder had higher PTSD symptoms and exposure to potentially traumatic events (PTEs) than veterans with PTSD alone. Higher ApoE cysteine residues per mole were associated with lower PTSD symptoms, indicating its protective nature. Finally, structural equation modeling showed that higher cysteine residues per mole indirectly predicted higher cognition, through lowering PTSD symptoms that negatively affect cognitive functioning. These analyses provide new information regarding the complex relationships between trauma exposure, symptom severity, genetic susceptibility and cognitive function in the context of PTSD in U.S. veterans. Strategies to use these results to improve holistic clinical care and further valuable research include: recommendation for the use of MoCA as a screening tool for cognitive function and referral to other providers, consideration of the impact of Pre-deployment trauma exposure on both current PTSD symptoms and cognitive function, and clarification on the importance of assessing ApoE using cysteine residues per mole to fully interpret risk and protective factors. Finally, these results, taken together using structural equation modelling, illustrate the intricacy of relationships between the many factors contributing to an individual’s presentation with PTSD, an important reminder when working with those experiencing this difficult condition.