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Potential for primary prevention of Alzheimer's disease: an analysis of population-based data.

Abstract

BACKGROUND

Recent estimates suggesting that over half of Alzheimer's disease burden worldwide might be attributed to potentially modifiable risk factors do not take into account risk-factor non-independence. We aimed to provide specific estimates of preventive potential by accounting for the association between risk factors.

METHODS

Using relative risks from existing meta-analyses, we estimated the population-attributable risk (PAR) of Alzheimer's disease worldwide and in the USA, Europe, and the UK for seven potentially modifiable risk factors that have consistent evidence of an association with the disease (diabetes, midlife hypertension, midlife obesity, physical inactivity, depression, smoking, and low educational attainment). The combined PAR associated with the risk factors was calculated using data from the Health Survey for England 2006 to estimate and adjust for the association between risk factors. The potential of risk factor reduction was assessed by examining the combined effect of relative reductions of 10% and 20% per decade for each of the seven risk factors on projections for Alzheimer's disease cases to 2050.

FINDINGS

Worldwide, the highest estimated PAR was for low educational attainment (19·1%, 95% CI 12·3-25·6). The highest estimated PAR was for physical inactivity in the USA (21·0%, 95% CI 5·8-36·6), Europe (20·3%, 5·6-35·6), and the UK (21·8%, 6·1-37·7). Assuming independence, the combined worldwide PAR for the seven risk factors was 49·4% (95% CI 25·7-68·4), which equates to 16·8 million attributable cases (95% CI 8·7-23·2 million) of 33·9 million cases. However, after adjustment for the association between the risk factors, the estimate reduced to 28·2% (95% CI 14·2-41·5), which equates to 9·6 million attributable cases (95% CI 4·8-14·1 million) of 33·9 million cases. Combined PAR estimates were about 30% for the USA, Europe, and the UK. Assuming a causal relation and intervention at the correct age for prevention, relative reductions of 10% per decade in the prevalence of each of the seven risk factors could reduce the prevalence of Alzheimer's disease in 2050 by 8·3% worldwide.

INTERPRETATION

After accounting for non-independence between risk factors, around a third of Alzheimer's diseases cases worldwide might be attributable to potentially modifiable risk factors. Alzheimer's disease incidence might be reduced through improved access to education and use of effective methods targeted at reducing the prevalence of vascular risk factors (eg, physical inactivity, smoking, midlife hypertension, midlife obesity, and diabetes) and depression.

FUNDING

National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care for Cambridgeshire and Peterborough.

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  • Publisher Full Text
  • Authors+Show Affiliations

    ,

    Psychology Department, Institute of Psychiatry, King's College London, London, UK.

    ,

    Medical Research Council Biostatistics, Institute of Public Health, Cambridge, UK.

    ,

    Department of Psychiatry, University of California, San Francisco, CA, USA; Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA; San Francisco VA Medical Center, San Francisco, CA, USA.

    ,

    Department of Psychiatry, University of California, San Francisco, CA, USA; Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA; Department of Neurology, University of California, San Francisco, CA, USA; San Francisco VA Medical Center, San Francisco, CA, USA.

    Institute of Public Health, University of Cambridge, Cambridge, UK. Electronic address: carol.brayne@medschl.cam.ac.uk.

    Source

    The Lancet. Neurology 13:8 2014 Aug pg 788-94

    MeSH

    Alzheimer Disease
    Databases, Factual
    Depression
    Diabetes Mellitus
    Educational Status
    Europe
    Global Health
    Health Surveys
    Humans
    Hypertension
    Motor Activity
    Obesity
    Population Surveillance
    Primary Prevention
    Risk Factors
    Smoking
    Smoking Prevention
    United States

    Pub Type(s)

    Journal Article
    Meta-Analysis
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    25030513

    Citation

    Norton, Sam, et al. "Potential for Primary Prevention of Alzheimer's Disease: an Analysis of Population-based Data." The Lancet. Neurology, vol. 13, no. 8, 2014, pp. 788-94.
    Norton S, Matthews FE, Barnes DE, et al. Potential for primary prevention of Alzheimer's disease: an analysis of population-based data. Lancet Neurol. 2014;13(8):788-94.
    Norton, S., Matthews, F. E., Barnes, D. E., Yaffe, K., & Brayne, C. (2014). Potential for primary prevention of Alzheimer's disease: an analysis of population-based data. The Lancet. Neurology, 13(8), pp. 788-94. doi:10.1016/S1474-4422(14)70136-X.
    Norton S, et al. Potential for Primary Prevention of Alzheimer's Disease: an Analysis of Population-based Data. Lancet Neurol. 2014;13(8):788-94. PubMed PMID: 25030513.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Potential for primary prevention of Alzheimer's disease: an analysis of population-based data. AU - Norton,Sam, AU - Matthews,Fiona E, AU - Barnes,Deborah E, AU - Yaffe,Kristine, AU - Brayne,Carol, PY - 2014/7/18/entrez PY - 2014/7/18/pubmed PY - 2014/9/16/medline SP - 788 EP - 94 JF - The Lancet. Neurology JO - Lancet Neurol VL - 13 IS - 8 N2 - BACKGROUND: Recent estimates suggesting that over half of Alzheimer's disease burden worldwide might be attributed to potentially modifiable risk factors do not take into account risk-factor non-independence. We aimed to provide specific estimates of preventive potential by accounting for the association between risk factors. METHODS: Using relative risks from existing meta-analyses, we estimated the population-attributable risk (PAR) of Alzheimer's disease worldwide and in the USA, Europe, and the UK for seven potentially modifiable risk factors that have consistent evidence of an association with the disease (diabetes, midlife hypertension, midlife obesity, physical inactivity, depression, smoking, and low educational attainment). The combined PAR associated with the risk factors was calculated using data from the Health Survey for England 2006 to estimate and adjust for the association between risk factors. The potential of risk factor reduction was assessed by examining the combined effect of relative reductions of 10% and 20% per decade for each of the seven risk factors on projections for Alzheimer's disease cases to 2050. FINDINGS: Worldwide, the highest estimated PAR was for low educational attainment (19·1%, 95% CI 12·3-25·6). The highest estimated PAR was for physical inactivity in the USA (21·0%, 95% CI 5·8-36·6), Europe (20·3%, 5·6-35·6), and the UK (21·8%, 6·1-37·7). Assuming independence, the combined worldwide PAR for the seven risk factors was 49·4% (95% CI 25·7-68·4), which equates to 16·8 million attributable cases (95% CI 8·7-23·2 million) of 33·9 million cases. However, after adjustment for the association between the risk factors, the estimate reduced to 28·2% (95% CI 14·2-41·5), which equates to 9·6 million attributable cases (95% CI 4·8-14·1 million) of 33·9 million cases. Combined PAR estimates were about 30% for the USA, Europe, and the UK. Assuming a causal relation and intervention at the correct age for prevention, relative reductions of 10% per decade in the prevalence of each of the seven risk factors could reduce the prevalence of Alzheimer's disease in 2050 by 8·3% worldwide. INTERPRETATION: After accounting for non-independence between risk factors, around a third of Alzheimer's diseases cases worldwide might be attributable to potentially modifiable risk factors. Alzheimer's disease incidence might be reduced through improved access to education and use of effective methods targeted at reducing the prevalence of vascular risk factors (eg, physical inactivity, smoking, midlife hypertension, midlife obesity, and diabetes) and depression. FUNDING: National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care for Cambridgeshire and Peterborough. SN - 1474-4465 UR - https://www.unboundmedicine.com/medline/citation/25030513/Potential_for_primary_prevention_of_Alzheimer's_disease:_an_analysis_of_population_based_data_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1474-4422(14)70136-X DB - PRIME DP - Unbound Medicine ER -