MCI is considered a putative AD prodromic stage, and MCI patients appear to be at an increased risk of developing AD at the rate of 10%-15% per year. Mitochondrial dysfunctionality has been proposed in the onset of AD. We propose that there may be a differential blood mitochondrial DNA (mtDNA) profile between MCI patients that do not progress to AD and those that do. One hundred MCI patients will be enrolled, and a genetic-clinical correlation will be carried out in a longitudinal prospective study. MCI patients will be evaluated through MR imaging and AD CSF biomarkers in the baseline study followed by a neuropsychological test and clinical control biannually. Blood samples will be obtained from MCI patients to carry out a genetic and epigenetic analysis of mitochondrial DNA. Two aspects will be tested in MCI patients: 1) the effect of specific mitochondrial polymorphisms already described in AD in combination with one located in the mtDNA control region already patented by our group, and 2) the effect of the mtDNA methylation pattern. MCI data analysis will be carried out in a retrospective way at the end of the second year. It is expected to establish a defined genetic/epigenetic mitochondrial panel to be tested in blood from MCI patients to evaluate their risk of developing AD