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AlzRisk Risk Factor Literature Search Strategy and Results

Risk Factor: Physical Activity
Risk Factor Type: Behavior, Metabolic
Current Understanding:
The tables below present a modest number of reports whose results, taken collectively, suggest an inverse association between physical activity and risk for both Alzheimer disease (AD) and dementia. Overall, these data suggest that physical activity is a modifiable protective factor. Results from other lines of research corroborate the value of physical activity in relation to cognitive decline in older adults, and support many collateral benefits of physical activity as well. However, specific aspects of the relationship between physical activity and cognitive outcomes remain to be clarified, including the optimal duration, intensity, and timing during the lifespan of physical activity necessary to reduce cognitive risks, and the durability of the benefits of physical activity. For a review of the putative mechanisms by which physical activity may influence AD risk and detailed commentary on interpreting the findings below in a broader context, please view the Discussion.
Last Search Completed: 06 July 2016 - Last content update released on 17 October 2016.

Risk Factor Overview


We searched MEDLINE and EMBASE for peer-reviewed articles reporting on the association between physical activity and Alzheimer’s disease (AD) incidence in cohort or nested case-control studies. The search returned 1548 unique citations that, after title and abstract review against our inclusion criteria, were narrowed down to 66 citations for full-text review. Four non-English articles were set aside for screening and subsequent review of any meeting our inclusion criteria. Of the remaining English articles, 14 fully met criteria for inclusion in our summary tables. We excluded 4 additional articles that otherwise met our inclusion criteria, but duplicated analyses from cohorts that contributed data to other included articles. We reviewed such duplications on a case-by-case basis, and selected the most informative article(s) based on sample size, follow-up time, exposure assessment or modeling, and appropriateness of analytic methods. In addition, we found one more article that met our inclusion criteria through previous literature searches related to other risk factors. Please see our methods section for more detail on our general systematic review methods.

We ran an update of the search in Pubmed and EMBASE covering articles published between November 1, 2011 and July 6, 2016, which returned 1,765 new citations. We excluded 1,745 citations that did not meet our inclusion criteria (e.g. topic not appropriate, review or editorial, animal studies). Fourteen studies were excluded after full text review because they did not meet inclusion criteria. Six articles were added to our Alzrisk tables from this updated search.

Search & Review Flowchart
Search Strategy
Selection of Papers Reporting on Data from the Same Cohort

Search Strategy Flowchart

Search Strategy

Using our systematic review methods, we developed similar search strategies (table below) for Pubmed, Ovid MEDLINE and EMBASE. We searched both Ovid MEDLINE and Pubmed to compare their capabilities. For this review, we found that Pubmed was sufficient for searching MEDLINE.

Search Strategy Table

Selection of Papers Reporting on Data from the Same Cohort

Some cohort studies produced multiple articles reporting on the association between physical activity and risk for Alzheimer’s disease. To avoid presenting duplicate results, we reviewed such articles on a case-by-case basis and selected the most informative article(s) based on sample size, follow-up time, exposure assessment or modeling, and appropriateness of analytic methods.

For each cohort listed below, we cite the duplicative articles we reviewed and give our rationale for their inclusion or exclusion. The full citation for each article is provided in the reference section.

Canadian Study of Health and Aging

We selected Laurin 2001 because Middleton 2007 reported on a small subsample of the same cohort.

Swedish Twin Registry

We included Gatz 2006 and Andel 2008 but excluded Crowe 2003. Crowe’s measure of leisure activities was a mixture of physical and non-physical activities. The Andel and Crowe papers were both included because they categorized physical activity differently in their analyses; physical activity was represented by 4 categories in Andel 2008, and by 2 categories in Gatz 2006.

Hisayama Study

We included Yoshitake 1995 and excluded Fujishima 2002. We excluded the Fujishima paper because it shared the same sample, analysis and results as the Yoshitake paper.

Honolulu-Asia Aging Study

We included Abbott 2004 and excluded Taaffe 2008. The relationship between AD onset and physical activity was studied in both the Abbott paper, which analyzed distance walked per day, and the Taaffe paper, which analyzed usual 24-hour physical activity within subgroups defined by physical function score at baseline. While the research question proposed by Taaffe et al. is important, the unclear temporal ordering between physical activity and physical function make it difficult to draw clear interpretations from the results.


Abbott RD, White LR, Ross GW, Masaki KH, Curb JD, Petrovitch H. Walking and dementia in physically capable elderly men. JAMA. 2004;292(12):1447-1453

Andel R, Crowe M, Pedersen NL, Fratiglioni L, Johansson B, Gatz M. Physical exercise at midlife and risk of dementia three decades later: A population-based study of Swedish twins. J Gerontol A Biol Sci Med Sci. 2008;63(1):62-66

Crowe M, Andel R, Pedersen NL, Johansson B, Gatz M. Does participation in leisure activities lead to reduced risk of Alzheimer's disease? A prospective study of Swedish twins. J Gerontol B Psychol Sci Soc Sci. 2003;58(5):P249-255

Fujishima M, Kiyohara Y. Incidence and risk factors of dementia in a defined elderly Japanese population: The Hisayama study. Ann N Y Acad Sci. 2002 Nov;977:1-8

Gatz M, Mortimer JA, Fratiglioni L, Johansson B, Berg S, Reynolds CA, Pedersen NL. Potentially modifiable risk factors for dementia in identical twins. Alzheimers Dement. 2006;2:110-117

Laurin D, Verreault R, Lindsay J, MacPherson K, Rockwood K. Physical activity and risk of cognitive impairment and dementia in elderly persons. Arch Neurol. 2001;58(3):498-504

Middleton LE, Kirkland SA, Maxwell CJ, Hogan DB, Rockwood K. Exercise: A potential contributing factor to the relationship between folate and dementia. J Am Geriatr Soc. 2007;55(7):1095-1098

Taaffe DR, Irie F, Masaki KH, Abbott RD, Petrovitch H, Ross GW, White LR. Physical activity, physical function, and incident dementia in elderly men: The Honolulu-Asia Aging Study. J Gerontol A Biol Sci Med Sci. 2008;63(5):529-535

Yoshitake T, Kiyohara Y, Kato I, Ohmura T, Iwamoto H, Nakayama K, Ohmori S, Nomiyama K, Kawano H, Ueda K, et al. Incidence and risk factors of vascular dementia and Alzheimer's disease in a defined elderly Japanese population: The Hisayama study. Neurology. 1995;45(6):1161-1168