Among the age-related diseases, the development of cognitive impairments, in particular dementia, is the most devastating for the individual and has great social and healthcare costs. Accurate information is needed about the prevalence and incidence of cognitive disorders and the physiology of the aging brain. In particular, only scarce data are available about the relationship between aging, cognitive status and nutritional factors. In order to address these issues, we planned the Conselice Study, a longitudinal study of physiological and pathological brain aging. The center involved in the study was the municipality of Conselice, (Province of Ravenna), in the Northern-Italian Region Emilia-Romagna. A total of 1,016 subjects aged 65 years and over was enrolled at baseline. Information about cognitive status at 4-years of follow-up was collected from 940 of them. These data have been used to estimate prevalence and incidence of dementia in the elderly Italian population and to investigate the possible role of homocysteine as a predictor of dementia.