This research aim to explore relationships between the presence of amyloid burden and cognitive performance, and its modulation by educational level. For this purpose we will combine Positron emission tomography (PET) imaging and neuropsychological assessment acquired on 3 groups of subjects, from two population-based cohorts "3C" and "AMIMage" The first group includes cognitively intact participants who will serve as controls, the second group, subjects with mild cognitive impairments without memory complaint and the third, subjects with both mild cognitive impairments and memory complaint.