A study found that 1 in 10 Americans over 65 have dementia, and Black adults are more likely to develop dementia than other groups.

Published in the journal JAMA Neurology, the study analyzed data from interviews and neuropsychological tests of nearly 3,500 random people over 65 years old from 2016 to 2017.

Researchers accounted for age, education, ethnicity, gender and race. Results showed that 22% of participants experienced mild cognitive impairment, an early stage of dementia. Those with less than a high school education were particularly vulnerable to developing both dementia and mild cognitive impairment.

Study authors noted that existing dementia research has often focused on people with a college education who identify as white.

“This study is representative of the population of older adults and includes groups that have been historically excluded from dementia research but are at higher risk of developing cognitive impairment because of structural racism and income inequality,” said Jennifer Manly, professor of neuropsychology at the Gertrude H. Sergievsky Center and the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain at Columbia University, in a CNN article.

The study found that 15% of participants who identified as Black tested positive for dementia and 22% had mild cognitive decline. Latino participants had lower rates of dementia (10%) but higher rates of mild cognitive impairment (28%). Only 9% of white people had dementia, while 21% had mild cognitive impairment.

Among adults 90 years and older, 35% tested positive for dementia and mild cognitive impairment—the highest rates observed in the study. Only 3% of adults between ages 65 and 69 tested positive for dementia.

“If we’re interested in increasing brain health equity in later life, we need to know where we stand now and where to direct our resources,” Manly said.