Therefore, in this study, we have investigated the circulating blood serum adiponectin levels, methylation of the CpG sites at − 74 nt of the ADIPOQ gene promoter, and expression of adiponectin receptors (AdipoR1 and AdipoR2) in peripheral blood mononuclear cells (PBMC) isolated from patients with AD in comparison with gender and age-matched healthy individuals since it may serve as a basis for the development of predictive blood-based biomarker of AD. The gene discussed is ADIPOR2; the disease is Alzheimer disease.