Anemia was defined according to World Health Organization criteria.<h4>Main outcomes and measures</h4>Incident dementia, diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria, and serum concentrations of phosphorylated tau 217 (p-tau217), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP), measured using Simoa assays. This evidence concerns the gene NEFL and anemia (phenotype).