Prevalence of Aging-Associated Cognitive Decline - AACD in an Italian elderly population: results from the cross sectional phase of the Italian PRoject on the Epidemiology of Alzheimer's disease (I.PR.E.A.).

BACKGROUND AND AIMS: The prevalence of the preclinical phase of dementia varies greatly, according to the diagnostic criteria and assessment procedures applied. The purpose of this study was to estimate the prevalence of cognitive impairment according to the Aging-Associated Cognitive Decline (AACD) diagnostic criteria in an Italian elderly population. METHODS: In a multicenter community-based prospective study, 4785 Italian subjects aged 65-84 years, randomly selected from the registries of 12 Italian municipalities, were assessed by personal and informant interviews, physical and neurological examinations and an extensive neuropsychological battery. RESULTS: Of these older subjects, 274 (9.2%) fulfilled all the AACD criteria, whereas 561 (18.8%) fulfilled only 3 of them (AACD-3). When the two groups diagnosed according to AACD criteria (AACD and AACD- 3) were merged, the prevalence was 28.0% (28.3% for men, 27.6% for women). Two other groups of subjects were also identified: a) Subjects with Objective evidence of Cognitive Decline without cognitive complaints (OCD), 508 (17.0%), i.e., subjects with documented neuropsychological deficits, although neither subjects nor informants reported cognitive complaints; and b) Subjects with Cognitive Complaints without objective demonstrable cognitive deficits (CC), 44 (1.5%), i.e., subjects and/or informants reported cognitive complaints without evidence of neuropsychological deficits. Thus, taking into account the additional OCD group, a total of 1343 persons with cognitive impairment without dementia (45.0%) was identified. CONCLUSIONS: On the basis of our results, we estimate that 45% of our population-based Italian sample aged 65-84 years had some kind of cognitive deficits without dementia.