Diabetes and Dementia: African Americans at Increased Risk

Diabetes, particularly poorly controlled diabetes, seems to be associated with late-life dementia. Most studies of the relationship have been conducted in primarily white populations. This is a concern because of the high prevalence of diabetes in African Americans. Researchers from the University of California, San Francisco, Johns Hopkins in Baltimore, MD, and the University of Mississippi at Jackson set out to determine the risks of dementia and rate of cognitive decline in non-white populations. Their results, published in the November 2014 issue of Neuroepidemiology, indicate African Americans with longstanding diabetes are at risk for accelerated cognitive decline.

They enrolled adult, middle-aged African Americans and whites who had previously enrolled in the Atherosclerosis Risk in Communities (ARIC) Brain MRI Study. They assessed verbal memory, processing speed, and verbal fluency in 1,886 participants, 49% of whom were African American, 4 times over 14 years. They compared cognitive change in participants with baseline diabetes and incident (diagnosed after baseline) diabetes to that of participants who did not have diabetes.

African Americans identified as diabetic at baseline had 41% greater annual decline in processing speed and 50% greater annual decline in verbal fluency than those without diabetes. The researchers suggest that this accelerated 14-year decline may reflect adverse effects of longer duration and more advanced diabetes.

African Americans with incident and whites with any kind of diabetes did not have pronounced cognitive decline.

In this study, African Americans with baseline diabetes had higher fasting blood glucose levels and were more likely to use anti-diabetes medication than whites with baseline diabetes. This is a surrogate marker for more advanced disease. Historic and persistent inequalities in the delivery of health care to African Americans who have diabetes may place them at greater risk of cognitive decline.