Study investigates why blacks have higher risk of cognitive impairment

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, an 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 was published online and will appear in the June print edition of 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 her 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). All participants were 65 or older in 1998.

Once the researchers took the various socioeconomic factors into account, 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.