One in five older Americans has type 2 diabetes, putting them at increased risk of developing Alzheimer’s disease and other forms of dementia. Now a new study finds that dementia risk is particularly high in African-Americans and Native Americans with diabetes, and lowest among Asian-Americans with the disease.
The study, the first to look at racial and ethnic differences in dementia risk among people with diabetes, looked at more than 22,000 men and women living in northern California. All had diabetes, but none had dementia, at the start of the study. Over the next 10 years, about one in six overall -- or one in five Native Americans or African-Americans -- developed Alzheimer’s or other forms of dementia.
"There were marked differences in rates of dementia over a 10-year period by racial and ethnic groups" said senior author Rachel Whitmer, a research scientist at the Kaiser Permanente Division of Research. "Moreover, the differences were not explained by diabetes-related complications, glycemic control or duration of diabetes. Nor were they altered by factors of age, gender, neighborhood deprivation index, body mass index or hypertension."
African-Americans and Native Americans have high rates of diabetes, and the findings add to growing concerns about the burden of dementia in these groups as well. Latinos, too, are disproportionately affected by diabetes, though the disease affects people of all races and ethnicities, and is becoming alarmingly common even among young people as well.
A number of studies have tied obesity, and in particular having lots of belly fat, with an increased risk of Alzheimer’s and other forms of dementia. Obesity is similarly linked to an increased risk of diabetes. Diabetes and poor blood sugar control is also linked to an increased risk for mild cognitive impairment, a condition marked by difficulties in thinking and learning that may progress to Alzheimer’s disease.
Diabetes may contribute to poor memory in various ways. The disease damages tiny blood vessels throughout the body, including the brain, which may be one reason why people with diabetes are, as a group, at higher risk of memory and thinking problems as they grow older. Diabetes also causes swings in blood sugar, or glucose, which may also damage brain cells.
It is important to note, though, that having diabetes does not mean that you will inevitably develop Alzheimer's. Rather, diabetes may put you at increased risk for developing these conditions. Similarly, many people who develop Alzheimer's do not have diabetes.
But the findings of this and other studies underscore the importance of prevention in helping to reduce Alzheimer's risk, regardless or your age, race or ethnicity. Maintaining lifestyle measures, like keeping weight down and following a regular exercise regimen, can be important in avoiding diabetes -- and may help in maintaining brain health.
Source: E. R. Mayeda, A. J. Karter, E. S. Huang, H. H. Moffet, M. N. Haan, R. A. Whitmer. “Racial/ethnic differences in dementia risk among older type 2 diabetes patients: The Diabetes and Aging Study.” Diabetes Care, 2013.