Researchers at UC Davis Health and Kaiser Permanente Division of Research have received a $24 million grant from the National Institute on Aging, part of the National Institutes of Health (NIH), to continue the Study of Healthy Aging in African Americans (STAR) for an additional five years.
STAR, which launched in 2017, follows a group of approximately 750 older adults to understand how behaviors and lifestyle may increase the risk of Alzheimer's disease and related dementias for Black and African Americans. The study is also trying to better understand the factors that may protect brain health.
Black Americans have the highest rate of Alzheimer's disease and related dementias of all ethnic and racial groups in the United States. Older Black Americans are about one-and-a-half to two times more likely than white Americans to be living with dementia or Alzheimer's.
Among Black Americans 70 years of age and older, 21.3% live with Alzheimer's. But information about potential risks in early life -; and ways to mitigate those risks -; relies almost exclusively on research conducted with white participants.
Rachel Whitmer, a professor in the departments of Public Health Sciences and Neurology and co-director of the UC Davis Alzheimer's Disease Research Center, and Paola Gilsanz, an epidemiologist and research scientist at Kaiser Permanente Division of Research, are the principal investigators of the study.
We are thrilled to continue this study for another five years so that we can further unravel what contributes to brain health and dementia risk in Black Americans. There have not been a lot of studies following this community from middle age into late life. But understanding the risk and protective factors throughout someone's life is key to improving brain health and reducing disparities."
Rachel Whitmer, professor in the departments of Public Health Sciences and Neurology and co-director of the UC Davis Alzheimer's Disease Research Center
Study follows participants' health and habits over time
Participants in the STAR study are Black adults living in the San Francisco Bay Area and the greater Sacramento region. They are long-term members of Kaiser Permanente Northern California, meaning the researchers have a wealth of health data as far back as the 1960s. This offers a unique opportunity to understand how factors earlier in life, such as hypertension in young adulthood, may contribute to brain health later.
"With the ability to further follow these individuals over time, we will be better able to understand the cognitive aging transition and how to reduce the risk of cognitive impairment in this important population," Gilsanz said.
The STAR participants are visited in their homes or local clinics and participate in surveys and cognitive tests looking at an array of health, behavioral and functional measures. Some participants also undergo magnetic resonance imaging (MRI) brain scans, a noninvasive way to view brain health.
The information collected by the researchers helps identify associations between behavioral and lifestyle factors, along with changes in the brain over time, to understand the risk factors and protective factors for dementia.
Identifying factors that hurt or help brain health
The first five years of STAR produced significant findings regarding factors that may contribute to late-life cognition. Researchers learned that:
- School segregation and timing of desegregation are associated with differences in late-life cognition
- Hypertension, diabetes and high cholesterol (hyperlipidemia) in adolescence, young adulthood and midlife are linked to poorer cognitive performance and more vascular brain injury later in life
- Birth in a "stroke-belt" state is associated with poorer cognitive function in late life
The study also identifies some potentially mitigating factors that might improve brain health:
- Study participants who read or played games weekly had better executive function than those who did not
- Study participants who volunteered several times a week later in life had the highest levels of executive function compared to those who did not volunteer
Researchers also found that attending a school with mostly Black students was associated with lower depressive symptoms later in life. Recent studies show a link between depression and dementia.
"Dr. Gilsanz and I are immensely grateful for our STAR participants," Whitmer said. "Their participation is leading to greatly improved knowledge about aging and brain health for Black Americans in the U.S. They are also showing us what can be done to reduce the disparity of diseases like Alzheimer's, which is expected to almost quadruple by 2060 for Black Americans."
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