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Cover of Preventing Alzheimer's Disease and Cognitive Decline

Preventing Alzheimer's Disease and Cognitive Decline

Evidence Reports/Technology Assessments, No. 193

, MD, MPH, , PhD, , MD, PhD, , MD, and , MD.

Duke Evidence-based Practice Center, Durham, North Carolina
Rockville (MD): Agency for Healthcare Research and Quality (US); .
Report No.: 10-E005

Structured Abstract

Objectives:

To assess whether previous research on purported risk or protective factors for Alzheimer’s disease (AD) and cognitive decline is of sufficient strength to warrant specific recommendations for behavioral, lifestyle, or pharmaceutical interventions/modifications targeted to these endpoints.

Data Sources:

MEDLINE® and the Cochrane Database of Systematic Reviews. Additional studies were identified from reference lists and technical experts.

Review Methods:

A group of experts in the field developed the list of factors to be evaluated in preparation for an upcoming National Institutes of Health (NIH) Office of Medical Applications of Research (OMAR) State-of-the-Science Conference addressing the prevention of AD and cognitive decline. We grouped the factors into the following categories: nutritional factors, medical conditions and prescription and non-prescription medications, social/economic/behavioral factors, toxic environmental factors, and genetics. Outcomes of interest were the development of AD or cognitive decline. Both observational and intervention studies were evaluated. Studies were evaluated for eligibility and quality, and data were abstracted on study design, demographics, intervention or predictor factor, and cognitive outcomes.

Results:

A total of 25 systematic reviews and 250 primary research studies were included. Only a few factors showed a consistent association with AD or cognitive decline across multiple studies, including both observational studies and randomized controlled trials (when available). Such factors associated with increased risk of AD and cognitive decline were: diabetes, epsilon 4 allele of the apolipoprotein E gene (APOE e4), smoking, and depression. Factors showing a fairly consistent association with decreased risk of AD and cognitive decline were: cognitive engagement and physical activities. A consistent association does not imply that findings were robust, as the data were often limited, and the quality of evidence was typically low. In addition, the modification of risk for reported associations was typically small to moderate for AD, and small for cognitive decline. Some of the factors that did not show an association with AD or cognitive decline in this review may still play an influential role in late-life cognition, but there was not sufficient evidence to draw this conclusion. Many of the factors evaluated are not amenable to randomization, so rigorous observational studies are required to assess their effect on AD and cognitive decline.

Conclusions:

The current research on the list of putative risk or protective factors is largely inadequate to confidently assess their association with AD or cognitive decline. Further research that addresses the limitations of existing studies is needed prior to be able to make recommendations on interventions.

Contents

540 Gaither Road, Rockville, MD 20850. www​.ahrq.gov

Acknowledgments: The authors thank the following individuals: for help with literature search and retrieval, Connie Schardt; for statistical support, Victor Hasselblad, Ph.D.; for assistance in the preparation of evidence tables, Remy Coeytaux, M.D., Ph.D.; Jennifer McDuffie, Ph.D.; Ravi Dhurjati, D.Phil.; Carolina Aponte Urdaneta, M.D.; and Katie Dore, P.A-C.; for project management, Julian Irvine, M.C.M.; for editorial assistance, Rebecca Gray, D.Phil.; and for research assistance, Alice Thacher and Vincent Miller.

Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services.1 Contract No. HHSA 290-2007-10066-I. Prepared by: Duke Evidence-based Practice Center, Durham, North Carolina.

Suggested citation:

Williams JW, Plassman BL, Burke J, Holsinger T, Benjamin S. Preventing Alzheimer’s Disease and Cognitive Decline. Evidence Report/Technology Assessment No. 193. (Prepared by the Duke Evidence-based Practice Center under Contract No. HHSA 290-2007-10066-I.) AHRQ Publication No. 10-E005. Rockville, MD: Agency for Healthcare Research and Quality. April 2010.

This report is based on research conducted by the Duke Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. HHSA 290-2007-10066-I). The findings and conclusions in this document are those of the author(s), who are responsible for its contents, and do not necessarily represent the views of AHRQ. No statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.

The information in this report is intended to help clinicians, employers, policymakers, and others make informed decisions about the provision of health care services. This report is intended as a reference and not as a substitute for clinical judgment.

This report may be used, in whole or in part, as the basis for development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

No investigators have any affiliations or financial involvement (e.g., employment, consultancies, honoraria, stock options, expert testimony, grants or patents received or pending, or royalties) that conflict with material presented in this report.

1

540 Gaither Road, Rockville, MD 20850. www​.ahrq.gov

Bookshelf ID: NBK47456
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