The elderly population is increasing more than any other sector of the population. Dementia, a prevalent condition in the elderly, increases disability, morbidity and mortality among older people. For these reasons the possibility of predicting progression and prognosis has enormous importance. Despite the fact that dementia has gained widespread recognition in the past few decades, the knowledge of its natural history, in terms of progression and prognosis are not yet completely understood. However, thanks to longitudinal research, which has only recently begun to proliferate, not only is better comprehension of the continuity of the cognitive decline possible, but also the identification of some prognostic factors.