| Disparities in Cognitive Functioning by Race/Ethnicity in the Baltimore Memory Study Brian S. Schwartz,1,2,3 Thomas A. Glass,2 Karen I. Bolla,4 Walter F. Stewart,1,2 Gregory Glass,5 Meghan Rasmussen,1 Joseph Bressler,4,6,7 Weiping Shi,1 and Karen Bandeen-Roche8 1Department of Environmental Health Sciences, Division of Occupational and Environmental Health, and 2Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA; 3Department of Medicine, and 4Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA; 5Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA; 6Department of Environmental Health Sciences, Toxicology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA; 7Department of Neurotoxicology, Kennedy Krieger Institute, Baltimore, Maryland, USA; 8Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA Abstract
The Baltimore Memory Study is a cohort study of the multilevel determinants of cognitive decline in 50-70-year-old randomly selected residents of specific city neighborhoods. Prior studies have demonstrated that cognitive function differs by race/ethnicity, with lower scores in minorities than in whites, but the underlying basis for these differences is not understood. Studies have differed in the rigor with which they evaluated and controlled for such important confounding variables as socioeconomic status (SES) , health-related behaviors, comorbid illnesses, and factors in the physical environment. The goal of this study was to describe differences in neurobehavioral test scores by race/ethnicity, before and after control for a four-dimensional measure of SES and health-related behaviors and health conditions, in a cross-sectional analysis of first visit data. Random samples of households in the study area were selected until enrollment goals were reached. Among the 2,351 persons on whom eligibility was determined, 60.8% were scheduled for an enrollment visit ; of these, 1,140 (81.3%) were enrolled and tested. These study participants were 34.3% male and 65.7% female and were from 65 Baltimore, Maryland, neighborhoods. After adjustment for age, sex, and testing technician, there were large and statistically significant differences in neurobehavioral test scores by race/ethnicity, with African-American scores lower than those for whites, for both men and women. After adjustment for individual SES (educational status, household income, household assets, and occupational status) , the average difference declined by 25.8%. After additional adjustment for SES, health-related behaviors and health conditions, and blood lead, the average difference declined another 10%, but large differences persisted ; African Americans had test scores that averaged 0.43 standard deviation lower than those for whites across all neurobehavioral tests. These differences were present in all cognitive domains, including tests that would not be characterized as susceptible to differential item functioning by race/ethnicity, suggesting that the results are not due to race/ethnicity-associated measurement error. Key words: cognitive function, health disparities, race/ethnicity, socioeconomic status. Environ Health Perspect 112:314-320 (2004) . doi:10.1289/ehp.6727 available via http://dx.doi.org/ [Online 24 November 2003]
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 the National Institute of Aging grant R01 AG19604 to B.S.S. The authors declare they have no competing financial interests. Received 8 September 2003 ; accepted 24 November 2003.
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