New York, Feb 11 (IANS): Examining dementia risk in a large population representing the diversity of the US, researchers have found the incidence of the brain disorder to be the lowest among Asian Americans.

The study compared six ethnic and racial groups within the same geographic population and found significant variation in dementia incidence among them.

"This is the only research that directly compares dementia for these six racial and ethnic groups, representing the true ageing demographic of the United States in a single study population," said study lead author Elizabeth Rose Mayeda, postdoctoral fellow at University of California, San Francisco.

The researchers found dementia incidence to be highest in Blacks and American Indian/Alaska Natives, lowest among Asian Americans, and intermediate among Latinos, Pacific Islanders and Whites.

The study population included 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.

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 researchers found that dementia incidence over the study period ranged from an average annual rate of 26.6 cases per 1,000 for Blacks, and 22.2 cases per 1,000 for American Indians/Alaskan Natives, to 15.2 cases per 1,000 for Asian Americans.

In between were Latinos and Pacific Islanders with an average annual rate of 19.6 cases per 1,000, and Whites with 19.3 per 1,000.

The results were published online in Alzheimer's & Dementia: The Journal of the Alzheimer's Association.