Dementia Risk Varies Significantly Across Racial/Ethnic Groups

In the first large-scale study of its kind, researchers at Kaiser Permanente and the University of California San Francisco (UCSF) found that rates of dementia risk vary across racial and ethnic groups.

Though similar studies on dementia risk have been performed in the past, they have only compared 1 or 2 racial/ethnic groups. In order to better represent the full diversity of the US populace, this is the first direct comparison of dementia rates among 6 different groups: African-Americans/Blacks, American Indians, Alaska Natives (AIAN), Latinos/Hispanics, Pacific Islanders/Native Hawaiians, non-Latino Whites, and Asian-Americans.

Elizabeth Rose Mayeda, PhD, et al. looked at 274,283 members of Kaiser Permanente Northern California (KPNC), an integrated healthcare delivery system in California, who were aged 60 years and older as of January 1, 1996, and had no dementia diagnosis as of January 1, 2000.

The researchers followed these cohort members for incident dementia until end of KPNC membership, death, or end of study period on December 31, 2013. Dementia diagnoses were identified from electronic medical records during this 14-year period based on the International Classification of Diseases, 9^th Revision. Those who identified as Other or Multiracial were excluded due to small sample size. All members had equal access to healthcare. Researchers adjusted for healthcare utilization and comorbidities in health conditions including depression, hypertension, diabetes, stroke and cardiovascular disease.

The study found that age-adjusted dementia incidence rates were highest among African-Americans and AIANS; intermediate for Latinos, Pacific Islanders, and Whites; and lowest for Asian-Americans. In most groups, rates were similar for women and men until the age of 90, when rates became higher for women; this difference was statistically significant for Whites.

According to the observations within this study, the following pattern has been predicted for individuals who survive dementia-free to age 65 that will be diagnosed with dementia over the next 25 years: 38% of African-Americans, 35% of AIANs, 32% of Latinos, 30% of Whites, 28% of Asian-Americans, and 25% of Pacific Islanders. Adjustments for healthcare utilization and comorbidities did not substantially explain differences in dementia incidence.

The researchers wrote that it is “unclear if these differences are due to genetic or social and behavior factors, but if social and behavior factors are the primary pathways, these findings suggest substantial reductions in dementia incidence are possible.”

Future research should incorporate the identification of life course determinants of the observed disparities, neuroimaging measures of the observed disparities, evaluating heterogeneity within racial/ethnic groups, and examining dementia outcomes after diagnosis.