Mild cognitive impairment: Disparity of incidence and prevalence estimates

United BioSource Corporation, Center for Epidemiology and Database Analytics, Lexington, MA, USA.
Alzheimer's & dementia: the journal of the Alzheimer's Association (Impact Factor: 12.41). 01/2012; 8(1):14-21. DOI: 10.1016/j.jalz.2011.01.002
Source: PubMed


The purpose of conducting this study was to identify areas of concordance and sources of variation for the published rates of prevalence and incidence associated with various definitions for mild cognitive impairment (MCI).
The study used systematic review of studies published in English since 1984. Studies were identified by searching MEDLINE and EMBASE databases. Population-based observational studies of incidence or prevalence of MCI and related terms were eligible for inclusion.
A total of 3,705 citations were identified, and 42 were accepted for inclusion; 35 included data on prevalence and 13 on incidence. The following four terms predominated: age-associated memory impairment (AAMI); cognitive impairment no dementia (CIND); MCI; and amnestic MCI (aMCI). Within each term, the operational definition varied. Substantial variation was observed for both incidence (MCI: 21.5-71.3; aMCI: 8.5-25.9 per 1,000 person-years) and prevalence of each definition of cognitive impairment (AAMI 3.6%-38.4%; CIND 5.1%-35.9%; MCI 3%-42%; aMCI 0.5%-31.9%). CIND and MCI showed increasing prevalence among older age groups, whereas age-specific rates of aMCI were lower and without any apparent age relationship.
Prevalence and incidence estimates associated with MCI vary greatly both between definitions and within a definition across the 42 publications. These wide differences pose a significant challenge to our understanding of the social burden of this disease. Enhancement and standardization of operational definitions of the subtypes of cognitive impairment could improve estimates of disease burden and provide a mechanism to assist in the identification of individuals at risk for future Alzheimer's disease and other dementias.

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    • ", 10 participants for 20s ~ 40s and 20 participants for 50s ~ 70s were separately recruited and gender ratio was balanced. Considering that the prevalence of brain disorders under 50s is relatively small (< 5%) compared to that over 50s (< 45.7%) (Ward et al., 2012), the participant aged 50s ~ 70s was recruited by two times than that aged 20s ~ 40s in the present study. "
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    Proceedings of the Human Factors and Ergonomics Society 59th Annual Meeting, Los Angeles, CA; 10/2015
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    • ". Though this work is specific to AD and not dementia, as AD is considered to be the most common type of dementia [20], similar age-specific trends and magnitude between the Europe and the United States is not unexpected. Sources of variability for prevalence of MCI and dementia have been previously described and potential causes include age and gender characteristics of study, diagnosis implementation, country, and year of study [16] [17]. For MCI in particular, a lack of consensus in criteria choice and implementation remains an important factor of heterogeneity: overall prevalence was more than doubled using DSM-IV versus Petersen criteria in the same population sample [8]. "
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