The progressive ageing of the general population and the consequent increase of the number of old people has made the typical medical problems of aged people more frequently observed, and particularly the problems related to the ageing brain. This new book is an updated overview of relevant aspects of cognitive decline associated with ageing. Within the wide landscape of brain ageing the authors reconsider the role of the main predisposing factors and risk factors on the development of various form of mental decline, from mild cognitive impairment to dementia. The strength of this book is the large, updated overview of the most recent data of scientific literature regarding the role of genetic, metabolic and environmental factors on the predisposition and onset of cognitive decline. Particular attention is paid to the dietary micro- and macronutrients and to their possible role in the pathogenesis of the various form of dementigen disorders.