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Mild Physical Impairment Predicts Future Diagnosis of Dementia of the Alzheimer's Type

Authors

  • Consuelo H. Wilkins MD, MS,

    Corresponding author
    1. Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, Missouri
    2. Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri
    3. Department of Surgery, Washington University School of Medicine, St. Louis, Missouri
    • Division of Geriatrics and Nutritional Science, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
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  • Catherine M. Roe PhD,

    1. Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, Missouri
    2. Department of Neurology, Washington University School of Medicine, St. Louis, Missouri
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  • John C. Morris MD,

    1. Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, Missouri
    2. Department of Neurology, Washington University School of Medicine, St. Louis, Missouri
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  • James E. Galvin MD, MPH

    1. Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, Missouri
    2. Center of Excellence on Brain Aging, New York University Langone Medical Center, New York, New York
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  • [Editorial Comments by Eric B. Larson pp 1210-1211]

Address correspondence to Consuelo H. Wilkins, Vanderbilt University School of Medicine, 1005 Dr. D.B. Todd Jr. Blvd, Biomedical Building, Nashville, TN 37208. E-mail: consuelo.h.wilkins@vanderbilt.edu

Abstract

Objectives

To determine whether mildly impaired physical function (based on performance-based assessment) is associated with development of dementia of the Alzheimer's type (DAT) in cognitively normal older adults.

Design

Longitudinal, observational study with yearly assessments of physical and cognitive function. Mean follow-up was 5 years.

Setting

Knight Alzheimer's Disease Research Center at Washington University, St. Louis, Missouri.

Participants

Four hundred thirty-five cognitively normal adults aged 60 and older participating in longitudinal studies of aging.

Measurements

Survival analyses were used to examine whether scores on the 9-item Physical Performance Test (PPT) predicted time to DAT diagnosis. Cox proportional hazards models were used to examine associations between PPT total scores and time to cognitive impairment and DAT; as well as the association between time and these events, adjusting for and simultaneously testing the effects of age, sex, education, and presence of one or more apolipoprotein (APOE) ε4 alleles.

Results

During the follow-up period, 81 participants developed DAT. Participants diagnosed with DAT were older (81.0 vs 74.2, P = .001) and had worse performance on the PPT (25.5 vs 28.1, P = .009) than those who remained cognitively normal. Time to DAT diagnosis was associated with PPT total score (hazard ratio (HR) = 0.89, 95% confidence interval (CI) = 0.86–0.93, P < .001) such that time to DAT diagnosis was longer for participants with higher physical performance scores. In the adjusted analysis, PPT score significantly predicted time to DAT diagnosis (HR = 0.94, 95% CI = 0.89–0.99, P = .02).

Conclusion

Mild physical impairment in cognitively normal older adults is associated with subsequent development of DAT. Although the physical impairment may be sufficiently mild that it is recognized only using performance-based assessments, its presence may predate clinically detectable cognitive decline.

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