Post-traumatic stress disorder in the Canadian Longitudinal Study on Aging: A genome-wide association study

Canada exhibits one of highest lifetime prevalence for post-traumatic stress disorder (PTSD), but the etiology of this debilitating mental health condition still remains largely unknown. This study aims to examine the genetics of PTSD in the Canadian Longitudinal Study on Aging (CLSA) to identify potential genetic factors involved in the development of PTSD. The CLSA sample was screened for primary (PTSD status) and secondary outcomes (avoidance, detachment, guardedness, and nightmares) based on the Primary Care PTSD Screen Scale (PC-PTSD). After GWAS quality control and whole-genome imputation, single-marker, gene-based, and polygenic risk score (PRS) analyses were performed. Based on available genotype and phenotype data, N = 16,535 individuals were selected for the analyses. While genome-wide analyses did not show significant findings for our primary and secondary outcomes, PRS analyses showed variable levels of association between PC-PTSD items with trauma, major depressive disorder, schizophrenia, bipolar disorder, educational attainment, and insomnia (p < 5e-4). This is the first GWAS of PTSD status and individual PC-PTSD items in a population sample of older adults from Canada. This study was also able to replicate findings from previous studies. Genetic investigations into individual symptom components of PTSD may help untangle the complex genetic architecture of PTSD.