Diagnostic criteria and prevalence of mild cognitive impairment in older adults living in the community: a systematic review and meta-analysis

Background: Mild Cognitive Impairment (MCI) is a disorder in which the patient presents a cognitive decline, but without negative impact on the activities of daily living. Objective: To carry out a systematic review of published studies that analyzed the prevalence of Mild Cognitive Impairment (MCI) in older adults living in the community, and the criteria used for the diagnosis of this disorder. Methods: A search was carried out in May 2017 using the descriptors: "epidemiology" or "prevalence", "mild cognitive impairment", and "community" in the PubMed, PsycInfo, SciELO, Web of Science, and Scopus databases. Two independent researchers extracted and documented the data. We used a random effect model to calculate pooled prevalence of MCI for overall studies and for each subgroup divided by diagnostic criteria. Results: We found initially 1996 articles, and we selected 35 studies. The prevalence of MCI in the selected studies ranged from 0.5% to 41.8%. The overall pooled prevalence of MCI was 17.3% (CI 95%, 13.8-20.8), with significant heterogeneity between estimates (I-2 = 99.6%). Discussion: The standardization of the diagnostic criteria for MCI, as well as the tests used in the cognitive evaluation, could allow the comparison between the studies and would be an important step in the researches of this area.