| Blood Lead Is a Predictor of Homocysteine Levels in a Population-Based Study of Older Adults Jyme H. Schafer,1,2 Thomas A. Glass,3 Joseph Bressler,4,5,6 Andrew C. Todd,7 and Brian S. Schwartz1,2,3 1Department of Environmental Health Sciences, Division of Occupational and Environmental Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA; 2Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA; 3Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA; 4Department of Environmental Health Sciences, Division of Toxicological Sciences, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA; 5Department of Neurology, Johns Hopkins University, Baltimore, Maryland, USA; 6Department of Neurotoxicology, Kennedy Krieger Institute, Baltimore, Maryland, USA; 7Department of Community and Preventive Medicine, Mount Sinai School of Medicine, New York, New York, USA Abstract
Lead and homocysteine are both associated with cardiovascular disease and cognitive dysfunction. We evaluated the relations among blood lead, tibia lead, and homocysteine levels by cross-sectional analysis of data among subjects in the Baltimore Memory Study, a longitudinal study of 1,140 randomly selected residents in Baltimore, Maryland, who were 50-70 years of age. Tibia lead was measured by 109Cd K-shell X-ray fluorescence. The subject population had a mean ± SD age of 59.3 ± 5.9 years and was 66.0% female, 53.9% white, and 41.4% black or African American. Mean ± SD blood lead, tibia lead, and homocysteine levels were 3.5 ± 2.4 µg/dL, 18.9 ± 12.5 µg/g, and 10.0 ± 4.1 µmol/L, respectively. In unadjusted analysis, blood lead and homocysteine were moderately correlated (Pearson's r = 0.27, p < 0.01) . After adjustment for age, sex, race/ethnicity, educational level, tobacco and alcohol consumption, and body mass index using multiple linear regression, results revealed that homocysteine levels increased 0.35 µmol/L per 1.0 µg/dL increase in blood lead (p < 0.01) . The relations of blood lead with homocysteine levels did not differ in subgroups distinguished by age, sex, or race/ethnicity. Tibia lead was modestly correlated with blood lead (Pearson's r = 0.12, p < 0.01) but was not associated with homocysteine levels. To our knowledge, these are the first data to reveal an association between blood lead and homocysteine. These results suggest that homocysteine could be a mechanism that underlies the effects of lead on the cardiovascular and central nervous systems, possibly offering new targets for intervention to prevent the long-term consequences of lead exposure. Key words: blood lead, cross-sectional study, homocysteine, tibia lead. Environ Health Perspect 113:31-35 (2005) . doi:10.1289/ehp.7369 available via http://dx.doi.org/ [Online 7 September 2004]
Address correspondence to B.S. Schwartz, Johns Hopkins Bloomberg School of Public Health, Division of Occupational and Environmental Health, 615 North Wolfe St., Room W7041, Baltimore, MD 21205 USA. Telephone: (410) 955-4130. Fax: (410) 955-1811. E-mail: bschwart@jhsph.edu. This work was supported by R01 AG19604 (B.S.S.) . The authors declare they have no competing financial interests. Received 30 June 2004 ; accepted September 7 2004.
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