Italian Project on Epidemiology of Alzheimer's disease (I.PR.E.A.): study design and methodology of cross-sectional survey

BACKGROUND AND AIMS: The purpose of this paper is to describe the design and diagnostic procedures of the multicenter community-based prospective Italian Project on the Epidemiology of Alzheimer's disease (I.PR.E.A.). The study is aimed at estimating the prevalence and incidence of Alzheimer's disease (AD) in the preclinical phase, examining the natural history of cognitive decline without dementia (mainly AD) in the Italian population, and identifying risk factors or health determinants related or associated with various health outcomes. METHODS: Both cross-sectional and longitudinal phases will be performed in 4800 elderly subjects aged 65-84 years. The sample will be selected from the registries of 12 Italian rural and urban municipalities, with an interval of one year between examinations. The study population will undergo several screening examinations, including personal and informant interviews by means of a structured ad hoc questionnaire, physical and neurological examination, laboratory tests, genetic markers and a neuropsychological battery. Neuroimaging screening will also be carried out in a subgroup of subjects positive for cognitive impairment without dementia. The longitudinal phase will include all subjects who, during the cross-sectional survey, are identified as affected by cognitive impairment without dementia, and will aim at assessing the incidence and natural history of cognitive impairment without dementia and the degree of disease progression from the earliest stage. This is the first systematic prospective study on the preclinical phase of AD in Italy.