Abstract
Objective: To investigate whether dementia risk can be estimated using only health deficits not known to predict dementia.
Methods: A frailty index consisting of 19 deficits not known to predict dementia (the nontraditional risk factors index [FI-NTRF]) was constructed for 7,239 cognitively healthy, community-dwelling older adults in the Canadian Study of Health and Aging. From baseline, their 5-year and 10-year risks for Alzheimer disease (AD), dementia of all types, and survival were estimated.
Results: The FI-NTRF was closely correlated with age (r2 > 0.96, p < 0.001). The incidence of AD and dementia increased exponentially with the FI-NTRF (r2 > 0.75, p < 0.001 over 10 years). Adjusted for age, sex, education, and baseline cognition, the odds ratio of dementia increased by 3.2%(p = 0.021) for each deficit (that was not known to predict dementia) accumulated, outperforming the individual cognitive risk factors. The FI-NTRF discriminated people with AD and all-cause dementia from those who were cognitively healthy with an area under the receiver operating characteristic curve of 0.66 ± 0.03.
Conclusions: Comprehensive re-evaluation of a well-characterized cohort showed that age-associated decline in health status, in addition to traditional risk factors, is a risk factor for AD and dementia. General health may be an important confounder to consider in dementia risk factor evaluation. If a diverse range of deficits is associated with dementia, then improving general health might reduce dementia risk.
Footnotes
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Study funding: Supported by operating grants from the Canadian Institutes of Health Research (MOP-209888) and the Nova Scotia Health Research Foundation (MED2006-2086), and by a fellowship from the Alzheimer Society of Canada. K.R. receives funding from the Dalhousie Medical Research Foundation as Kathryn Allen Weldon Professor of Alzheimer Research.
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- 3MS=
- Modified Mini-Mental State Examination;
- AD=
- Alzheimer disease;
- AR=
- attributable risk;
- AUC=
- area under the curve;
- CI=
- confidence interval;
- CSHA=
- Canadian Study of Health and Aging;
- DSM-III-R=
- Diagnostic and Statistical Manual of Mental Disorders, 3rd edition, revised;
- FI-NTRF=
- frailty index of nontraditional risk factors;
- OR=
- odds ratio;
- ROC=
- receiver operating characteristic
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Editorial, page 206
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Supplemental data at www.neurology.org
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- Received September 17, 2010.
- Accepted December 22, 2010.
- Copyright © 2011 by AAN Enterprises, Inc.
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