ABO blood group antigens are expressed on red blood cell membranes and also on the surface of other human cells and tissues, including platelets, neurons, epithelia, and vascular endothelium. A substantial body of evidence links ABO antigens with the pathogenesis of various systemic diseases, particularly cardiovascular diseases (CVD). In vivo animal studies indicate a relevant role of the ABO locus in neurogenesis of sensory cells (olfactory system and inner ear). Thus, the clinical relevance of the ABO blood system may transcend transfusion/transplantation medicine, with potential (coagulation-related) modulatory effects on relevant dementia risk pathways including CVD and sensory impairments like hearing loss. Although some studies investigated associations between ABO blood groups, age-related neurodegeneration and dementia risk, most were conducted in high-income Western populations and yielded inconsistent findings.

This is the first cross-continental study on the ABO And Rh blood group phenotypes in relation to dementia-spectrum outcomes. The findings assess the critical need for scalable and cost-effective population-level dementia risk prediction models to inform public health policies and intervention strategies, particularly in low-income Global South regions facing a projected rise in dementia prevalence.