An epidemiologist at the UCLA Fielding School of Public Health is investigating the extent to which cumulative lifetime exposure to elevated blood pressure contributes to racial disparities in Alzheimer’s disease and related dementias. Various studies have indicated that people who are African-American and more than 60 years of age have a 40-100 percent higher incidence of dementia than people who are non-Latino white and in the same age bracket. Although hypertension is a known dementia risk factor, previous research has not shown that higher rates of hypertension among people who are African-American contribute to this disparity.
Dr. Elizabeth Rose Mayeda, assistant professor in the Fielding School’s department of epidemiology, suspects an important limitation of prior research on blood pressure and dementia risk is that it has looked at elevated blood pressure only as a single point in time, rather than studying the impact it can have over a lifetime. “By capturing cumulative exposure to elevated blood pressure throughout adulthood, we get a better representation of the impact than with a single snapshot, and are therefore able to better understand the relationship between blood pressure and Alzheimer’s disease and related dementias,” Dr. Mayeda says.
As principal investigator of a National Institutes of Health (NIH) grant (Racial Disparities in Alzheimer’s Disease and Related Dementias: The Role Of Blood Pressure Throughout Adulthood 4R00AG053410-03), Dr. Mayeda is analyzing 50 years of data for Kaiser Permanente of Northern California health plan members. Dr. Mayeda and her colleagues are using the data to compare rates of dementia among people who self-identify as African-American, non-Latino white, Latino or Asian-American, and to look at survival after dementia diagnosis by racial group.
Dr. Mayeda is also building a model that estimates blood pressure trajectories and dementia outcomes. “The incidence of Alzheimer’s and related dementias increases with age, but that doesn’t mean that we can simply compare dementia rates across race groups by age,” Dr. Mayeda says. “There are major racial disparities in life expectancy, which have to be taken into account when we examine the determinants of racial disparities in dementia.” To ensure that all applied researchers have access to the methods that are being used in the study, Dr. Mayeda is leading the Methods for Longitudinal Studies in Dementia (MELODEM) selection working group, an international and interdisciplinary initiative to improve the quality of statistical methods used in dementia research.
“Understanding the mechanisms behind racial disparities in the incidence of Alzheimer’s and related dementias is important for understanding which public health interventions will have the biggest impact,” Dr. Mayeda says. “For instance, if we identify sensitive periods for the effect of hypertension on risk of dementia, such as hypertension in your 30s, this could influence clinical guidelines and allow for the targeting we need to prevent and reduce ethnic and racial disparities in dementia incidence overall.”