The first study to look at dementia risk in a population representing the diversity of the United States finds dementia incidence to be highest in African Americans and lowest in Asian Americans

The rate of occurrence of dementia in African Americans was found to be 65% higher than Asian Americans. The scientists compared dementia incidence across six racial and ethnic groups – Whites, Asian-Americans, Latinos, African Americans, American Indians/Alaskan Natives, and Pacific Islanders. "Most research on disparities in dementia includes only one to two racial and ethnic groups, for example only Whites and African Americans," said study first author Elizabeth Rose Mayeda, Ph.D., Postdoctoral Fellow at University of California, San Francisco in the Department of Epidemiology and Biostatistics. "Our study is the only work that compares dementia for these six racial and ethnic groups representing the aging demographic of the United States in a single study population. It is also the first study to look at incidence of dementia in Pacific Islanders and American Indians." The researchers found that dementia incidence over the 14-year study period ranged from an average annual rate of 26.6 cases of dementia per 1,000 people for African-Americans, and 22.2 cases per 1,000 people for American Indians/Alaskan Natives, to 15.2 cases per 1,000 people for Asian-Americans. In between were Latinos and Pacific Islanders with an average annual rate of 19.6 cases per 1,000 people, and whites with 19.3 per 1,000. Using the observed dementia incidence rates and a widely accepted method of calculating a person's lifetime risk for developing a disease, the researchers estimated the percentage of individuals free of dementia before age 65 in each racial and ethnic group who can expect to be diagnosed with dementia over the next 25 years. The projections were 38% of African Americans, 35% of American Indians/Alaskan Natives, 32% of Latinos, 25% of Pacific Islanders, 30% of Whites, and 28% of Asian Americans.