However, no significant difference was found between AD or MCI patients and HCs in terms of platelet counts, mean corpuscular volume, red cell distribution width, mean platelet volume, and CD4<sup>+</sup> T, CD3<sup>+</sup> T, or natural killer cell counts.<h4>Conclusion</h4>Changes in peripheral blood cell profiles, particularly involving leukocyte, lymphocyte, neutrophil, and CD8<sup>+</sup> T cell counts, as well as the NLR and the CD4/CD8 ratio, are closely associated with AD. This evidence concerns the gene CD8A and Alzheimer disease.