The data comprise concentrations of complement and AT(N) proteins in plasma, measured via ELISAs, and genetic analyses from a cohort of AD patients and controls. Sample metadata such as participant ID, patient phenotype (controls, early-onset AD and late-onset AD), APoE status (33, 34, 44 denoting whether the individuals are homozygous for the minor – 4 - or major – 3 - allele or heterozygous for both), age at sample inclusion and biological sex (male or female). Each plasma protein header contains information about the protein name and concentration units.