IGHM and Alzheimer disease: A novel serum‐based protein profile with eight proteins—serum amyloid A4, pro‐platelet basic protein (PPBP), platelet factor 4, ApoA4, coagulation factor X, carboxypeptidase B2, complement C1s, and immunoglobulin heavy constant mu (IGHM)—was found and could identify AD case from controls with AUC of 92.3%.92