Hemoglobin level in older persons and incident Alzheimer disease
Prospective cohort analysis
- R.C. Shah, MD,
- A.S. Buchman, MD,
- R.S. Wilson, PhD,
- S.E. Leurgans, PhD and
- D.A. Bennett, MD
- From the Rush Alzheimer's Disease Center (R.C.S., A.S.B., R.S.W., S.E.L., D.A.B.), Department of Family Medicine (R.C.S.), Department of Neurological Sciences (A.S.B., S.E.L., D.A.B.), and Department of Behavioral Science (R.S.W.), Rush University Medical Center, Chicago, IL.
- Address correspondence and reprint requests to Dr. Raj C. Shah, Rush Alzheimer's Disease Center, Rush University Medical Center, Armour Academic Facility, Suite 1038, 600 South Paulina St., Chicago, IL 60612 Raj_C_Shah{at}rush.edu
Abstract
Objective: To test the hypothesis that level of hemoglobin is associated with incident Alzheimer disease (AD).
Methods: A total of 881 community-dwelling older persons participating in the Rush Memory and Aging Project without dementia and a measure of hemoglobin level underwent annual cognitive assessments and clinical evaluations for AD.
Results: During an average of 3.3 years of follow-up, 113 persons developed AD. In a Cox proportional hazards model adjusted for age, sex, and education, there was a nonlinear relationship between baseline level of hemoglobin such that higher and lower levels of hemoglobin were associated with AD risk (hazard ratio [HR] for the quadratic of hemoglobin 1.06, 95% confidence interval [CI] 1.01–1.11). Findings were unchanged after controlling for multiple covariates. When compared to participants with clinically normal hemoglobin (n = 717), participants with anemia (n = 154) had a 60% increased hazard for developing AD (95% CI 1.02–2.52), as did participants with clinically high hemoglobin (n = 10, HR 3.39, 95% CI 1.25–9.20). Linear mixed-effects models showed that lower and higher hemoglobin levels were associated with a greater rate of global cognitive decline (parameter estimate for quadratic of hemoglobin = −0.008, SE −0.002, p < 0.001). Compared to participants with clinically normal hemoglobin, participants with anemia had a −0.061 z score unit annual decline in global cognitive function (SE 0.012, p < 0.001), as did participants with clinically high hemoglobin (−0.090 unit/year, SE 0.038, p = 0.018).
Conclusions: In older persons without dementia, both lower and higher hemoglobin levels are associated with an increased hazard for developing AD and more rapid cognitive decline.
Footnotes
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Study funding: Supported by the NIH/NIA R01AG17917 and R01AG24480, the Illinois Department of Public Health, and the Robert C. Borwell Endowment Fund.
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Editorial, page 206
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Supplemental data at www.neurology.org
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- AD=
- Alzheimer disease;
- CI=
- confidence interval;
- FEV1=
- forced expiratory volume in 1 second;
- FVC=
- forced vital capacity;
- HR=
- hazard ratio;
- MCI=
- mild cognitive impairment
- Received September 3, 2010.
- Accepted December 22, 2010.
- Copyright © 2011 by AAN Enterprises, Inc.
