Abstract
Updated information on the epidemiology of dementia due to Alzheimer's disease (AD) is needed to ensure that adequate resources are available to meet current and future healthcare needs. We conducted a systematic review and meta-analysis of the incidence and prevalence of AD. The MEDLINE and EMBASE databases were searched from 1985 to 2012, as well as the reference lists of selected articles. Included articles had to provide an original population-based estimate for the incidence and/or prevalence of AD. Two individuals independently performed abstract and full-text reviews, data extraction and quality assessments. Random-effects models were employed to generate pooled estimates stratified by age, sex, diagnostic criteria, location (i.e., continent) and time (i.e., when the study was done). Of 16,066 abstracts screened, 707 articles were selected for full-text review. A total of 119 studies met the inclusion criteria. In community settings, the overall point prevalence of dementia due to AD among individuals 60+ was 40.2 per 1000 persons (CI95%: 29.1-55.6), and pooled annual period prevalence was 30.4 per 1000 persons (CI95%: 15.6-59.1). In community settings, the overall pooled annual incidence proportion of dementia due to AD among individuals 60+ was 34.1 per 1000 persons (CI95%: 16.4-70.9), and the incidence rate was 15.8 per 1000 person-years (CI95%: 12.9-19.4). Estimates varied significantly with age, diagnostic criteria used and location (i.e., continent). The burden of AD dementia is substantial. Significant gaps in our understanding of its epidemiology were identified, even in a high-income country such as Canada. Future studies should assess the impact of using such newer clinical diagnostic criteria for AD dementia such as those of the National Institute on Aging-Alzheimer's Association and/or incorporate validated biomarkers to confirm the presence of Alzheimer pathology to produce more precise estimates of the global burden of AD.
Highlights
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder leading to cognitive impairment, neuropsychiatric symptoms, disability, dependency, caregiver burden, substantial healthcare expenditures and premature death.[1,2,3] Up to 70% of the dementias occurring in older adults are attributed in whole or in part to AD.[4]
The last systematic review of the global incidence of dementia due to AD was published in 2008.10 While the age-specific incidence rate of AD dementia doubles approximately every 5.5 years in older populations[11] and several studies have produced estimates stratified by sex and geographic region,[10,12,13,14] an unexplored issue is the heterogeneity produced by differing diagnostic criteria and study setting
Among the 176 eligible papers meeting the inclusion criteria, 57 were excluded, as they did not report on the incidence or prevalence of AD dementia
Summary
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder leading to cognitive impairment, neuropsychiatric symptoms, disability, dependency, caregiver burden, substantial healthcare expenditures and premature death.[1,2,3] Up to 70% of the dementias occurring in older adults are attributed in whole or in part to AD.[4]. Updated information on the epidemiology of dementia due to AD is needed if we are to ensure that adequate resources are mobilized to deal with the needs of those with this condition and their families. Such studies can inform prevention strategies and approaches to management. Updated information on the epidemiology of dementia due to Alzheimer’s disease (AD) is needed to ensure that adequate resources are available to meet current and future healthcare needs.
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