Why are blacks at higher risk for cognitive impairment?

EAST LANSING, Mich. -- Social and economic disadvantages play a significant role in why blacks face a much higher risk than whites of developing cognitive impairment later in life, indicates a national study led by a Michigan State University sociologist.

The odds that blacks will develop cognitive impairment, including dementia, in later life were 2.52 times greater than the odds for whites. Much of that racial disparity was explained by childhood disadvantages, such as growing up poor and in the segregated South, and lower socioeconomic status in adulthood, particularly educational attainment.

Surprisingly, racial differences in health problems, such as heart disease and diabetes, and health behaviors, such as smoking and drinking, did not explain much of the racial gap in cognitive impairment, said Zhenmei Zhang, MSU associate professor of sociology.

While the findings do not fully explain blacks' higher risk of cognitive impairment, they point to a strong need for policymakers to focus more on reducing racial gaps in socioeconomic resources over the lifespan, she said. The federally funded study is published in the Journal of Health and Social Behavior.

"Social policies such as increasing educational resources in low-income communities, providing economic support to poor students and their families, improving graduation rates in high schools and colleges, and eliminating discrimination against blacks in the job market may significantly reduce racial disparities in cognitive impairment in later life," Zhang said.

Zhang and colleagues analyzed survey data from 8,946 participants in the Health and Retirement Study. The information was collected in multiple waves over a 12-year period (1998-2010); participants were aged 65 or older at the start of the study.

Once the researchers took into account the various socioeconomic factors, which include childhood disadvantages, the odds ratio of cognitive impairment between blacks and whites - or the racial gap - was reduced considerably, from 2.52 to 1.45. That means socioeconomic factors explained a significant amount of the racial gap.

Cognitive impairment among the elderly is a growing problem - spending on dementia care alone exceeds $100 billion a year in the United States - but it hits blacks particularly hard, Zhang noted. The Alzheimer's Association has identified Alzheimer's disease among blacks as an emerging public health crisis.

"As people live longer and longer, it becomes an even bigger issue," Zhang said.

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Her co-authors on the study were Mark Hayward, professor at the University of Texas, and Yan-Liang Yu, doctoral student at MSU. The study received funding from the National Institute on Aging and the National Institute of Child Health and Human Development, both part of the National Institutes of Health.

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