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This Article Full Text Full Text (PDF) CME: Take the course for this article: Volume 67, Number 9, November 14, 2006 Data Supplement All Versions of this Article: 01.wnl.0000239836.26142.c5v1 67/9/1556    most recent Correspondence: Submit a response Alert me when this article is cited Alert me when Correspondence are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shih, R. A. Articles by Schwartz, B. S. Search for Related Content PubMed PubMed Citation Articles by Shih, R. A. Articles by Schwartz, B. S. Related Collections All Neuropsychology/Behavior All Cognitive Disorders/Dementia All Toxicology

Environmental lead exposure and cognitive function in community-dwelling older adults

From the Departments of Mental Health (R.A.S., M.C.C.), Epidemiology (T.A.G., B.S.S.), Biostatistics (K.B.-R.), and Environmental Health Sciences (K.I.B., B.S.S.), Johns Hopkins Bloomberg School of Public Health, and Departments of Medicine (B.S.S.) and Neurology (K.I.B.), Johns Hopkins Medical Institutions, Baltimore, MD; and Department of Community and Preventive Medicine (A.C.T.), Mount Sinai School of Medicine, New York, NYS. is currently at the Division of Epidemiology, Statistics, and Prevention Research, National Institute of Child Health and Human Development, Rockville, MD.

Address correspondence and reprint requests to Dr. Brian S. Schwartz, Division of Occupational and Environmental Health, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Room W7041, Baltimore, MD 21205; e-mail: bschwart{at}jhsph.edu

Objective: To determine if long-term exposure to high levels of lead in the environment is associated with decrements in cognitive ability in older Americans.

Methods: We completed a cross-sectional analysis using multiple linear regression to evaluate associations of recent (in blood) and cumulative (in tibia) lead dose with cognitive function in 991 sociodemographically diverse, community-dwelling adults, aged 50 to 70 years, randomly selected from 65 contiguous neighborhoods in Baltimore, MD. Tibia lead was measured with ¹⁰⁹Cd induced K-shell X-ray fluorescence. Seven summary measures of cognitive function were created based on standard tests in these domains: language, processing speed, eye-hand coordination, executive functioning, verbal memory and learning, visual memory, and visuoconstruction.

Results: The mean (SD) blood lead level was 3.5 (2.2) µg/dL and tibia lead level was 18.7 (11.2) µg/g. Higher tibia lead levels were consistently associated with worse cognitive function in all seven domains after adjusting for age, sex, APOE-4, and testing technician (six domains p 0.01, one domain p 0.05). Blood lead was not associated with any cognitive domain. Associations with tibia lead were attenuated after adjustment for years of education, wealth, and race/ethnicity.

Conclusions: Independent of recent lead dose, retained cumulative dose resulting from previous environmental exposures may have persistent effects on cognitive function. A portion of age-related decrements in cognitive function in this population may be associated with earlier lead exposure.

Additional material related to this article can be found on the Neurology Web site. Go to www.neurology.org and scroll down the Table of Contents for the November 14 issue to find the title link for this article.

Editorial, see page 1536

This article was previously published in electronic format as an Expedited E-Pub on September 13, 2006, at www.neurology.org.

Disclosure: The authors report no conflicts of interest.

Received February 22, 2006. Accepted in final form July 17, 2006

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