ABO and dementia: Using the Scandinavian Donation and Transfusion (SCANDAT) database, we have previously studied associations between ABO blood groups and cancer subtypes, cardiovascular and thromboembolic disease, the occurrence of dementia and degradation of bioprosthetic aortic valves in relation to ABO blood group (Vasan et al., 2016a; Persson et al., 2019; Vasan et al., 2016b; Vasan et al., 2015).