Association of Oxidative Stress on Cognitive Function: A Bidirectional Mendelian Randomisation Study

The purpose of this study was to investigate the relationship between oxidative stress and cognitive function, encompassing cognitive performance, intelligence, memory, reaction time, speech and vision by a bidirectional Mendelian randomisation study. Independent genetic variants associated with glutathione S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX), peroxiredoxin (PRDX), sulfhydryl oxidase (SOX) and thyroid peroxidase (TPO) were explored using a genome-wide association study (GWAS). The inverse variance weighted (IVW) or Wald ratio method was employed to ascertain the relationship between antioxidant enzymes and cognitive function. The MR analyses indicated that the MR effect estimates of GST (β = 0.0352, P = 0.0047, FDR = 0.0164) and TPO (β = 0.0531, P = 0.0003, FDR = 0.0021) were significantly associated with cognitive performance elevation. Furthermore, genetically predicted GST (β = 0.0334, P = 0.0043, FDR = 0.0151) and TPO (β = 0.0496, P = 0.0031, FDR = 0.0151) were found to be associated with high intelligence. Additionally, there were also some associations of SOX (β = 0.0243, P = 0.0283, FDR = 0.066) on high cognitive performance, TPO (β = 0.1189, P = 0.0315, FDR = 0.2205) on larger maximum digits remembered correctly, and SOX (β = - 0.2435, P = 0.0395, FDR = 0.1185) on reaction time. Nevertheless, the associations between antioxidant enzymes and speech and linguistic disorders, as well as visual disturbances, were not significant. We did not find reverse causation between antioxidant enzymes and cognitive function traits. This study provides evidence of potential causal relationships between oxidative stress and cognitive function.