A Multicenter national prospective cohort study including at least 2300 individuals consecutively recruited from French Research Memory Centers and followed-up over 5 years.
Inclusion Criteria: * Aged 18 years and above * Having at least a light cognitive deficit defined as performing worse than one standard deviation to the mean (compared to age and educational norms) in one or more cognitive domains (assessed from a neuropsychological tests battery exploring memory, language, praxis, vision, executive functions); this deviation being identified for the first time by tests performed less than 6 months preceding date of inclusion * Or having isolated cognitive complaint regardless of its duration while being 60 years and older * Clinical Dementia Rating scale \<=0.5 and not demented * Visual and auditory acuity adequate for neuropsychological testing * Having signed an informed consent * Being affiliated to health insurance Exclusion Criteria: * Being under guardianship * Residence in skilled nursing facility * Pregnant or breast feeding women * Alzheimer's disease caused by gene mutations * Meeting brain MRI exclusion criteria (pacemakers, aneurysm clips, artificial heart valves, ear implants, metal fragments or foreign objects in the eyes, skin, or body) or refusing MRI * Having a neurological disease such as: treated epilepsy, treated Parkinson's disease, Huntington disease, brain tumour, subdural haematoma, progressive supranuclear palsy, history of head trauma followed by persistent neurological deficits * Stroke that has occurred in the last three months * Schizophrenia history (DSM-IV criteria) * Illiteracy, is unable to count or to read