US Dementia Incidence Highest Among African Americans and American Indians

The first study to look at dementia risk in a population accurately representing the diversity of the United States finds dementia incidence to be highest among African Americans and American Indians/Alaskan Natives; intermediate among Latinos, Pacific Islanders, and whites; and lowest among Asian Americans. 

The study, published online ahead of print in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, analyzed data from more than 274,000 northern California members of Kaiser Permanente, the nation’s largest private integrated health care system with more than 10 million members (doi: 10.1016/j.jalz.2015.12.007). 

The researchers used electronic health records covering patient visits over 14 years—from January 2000 through December 2013—to identify participants diagnosed with dementia as well as their race and ethnicity. The dementia diagnoses included Alzheimer’s disease, vascular dementia, and non-specific dementia.

The researchers found that dementia incidence over the 14-year study period varied greatly among racial and ethnic groups: 26.6 cases of dementia per 1000 people for African-Americans, 22.2 cases per 1000 people for American Indians/Alaskan Natives, 19.6 cases per 1000 people for Latinos and Pacific Islanders, 19.3 per 1000 people for whites, and 15.2 cases per 1000 people for Asian-Americans.

As members of the same health care system, all study participants had regular access to medical care during the study period. Despite this, and even after accounting for other illnesses, the disparities in dementia incidence remained.

Using the observed dementia incidence rates to calculate each person’s lifetime risk for developing dementia, the researchers estimated that the percentages of individuals free of dementia before age 65 who can expect to be diagnosed with dementia over the next 25 years were 38% among African Americans, 35% among American Indians/Alaskan Natives, 32% among Latinos, 30% among whites, 28% among Asian Americans, and 25% among Pacific Islanders.

“Even in the lowest risk groups in the study, the lifetime risk of developing dementia is high,” said study senior author Rachel Whitmer, PhD, Epidemiologist at Kaiser Permanente Northern California, CA. “Our projections indicate that in every racial and ethnic group, over one in four people who survive to age 65 can expect to be diagnosed with dementia in their lifetime.”

Whitmer concluded, “Based on the present study, we cannot determine the extent to which genetic or social and behavioral factors contribute to the observed patterns. But if social and behavioral factors are the primary pathways, these findings suggest substantial reductions in dementia incidence are possible.”—Amanda Del Signore