Dementia is one of the most troubling neurodegenerative syndrome whose prevalence and incidence is strongly increasing. The etiology and physiopathology of the process that causes dementia are still controversial and largely unknown. So it is of paramount importance to isolate risk and protection factors related to dementia syndrome and Alzheimer disease. These meager known factors (biological, as well as social and neuropsychological) can be better investigated through a multidimensional longitudinal study in a homogeneous population by age and place.