The stress and hardship experienced by many Black Americans may increase the risk of cognitive decline and dementia later in life, according to new research from the University of Georgia.
In a study of 694 aging Black Americans, UGA researchers found that struggles with severe depression, loneliness and a decline in the availability of an important neurotransmitter are important factors in cortical aging, defined as the difference between an individual’s actual brain age and their chronological age.
Accelerated brain aging is a primary determinant of cognitive decline and dementia. By focusing on Black Americans, the team hoped to explain why they are nearly twice as likely as white Americans to develop dementia as they age.
“The problem is African Americans haven’t been studied nearly as much as white Americans. Most of what we know about Alzheimer’s or accelerated brain aging is based on white people,” said Ron Simons, Regents’ Professor in the Franklin College of Arts and Sciences Department of Sociology and the primary investigator on the study. “It turns out that the stress and hardship experienced by many African Americans takes its toll on their brains and increases risk for dementia later in life.”
Simons, also a fellow in UGA’s Center for Family Research, and collaborators investigated the relationship between brain aging and three risk factors: loneliness, depression and brain-derived neurotrophic factor (BDNF). BDNF is a neurotransmitter that drives neuronal survival, growth and plasticity, essential factors to learning and memory.Relying on 10 years of participant data, the researchers found that all three risk factors predicted accelerated brain aging, but the effects were especially powerful for loneliness and BDNF. Severe depression and loneliness are two behavioral markers that have been linked to increased risk for dementia.
“Depression has been shown to impact the brain by shrinking and compromising the hippocampus, which plays a major role in retaining memory,” Simons said. “At the same time, loneliness, which often causes depression, may well have an impact on brain aging. Humans are wired to be social. We want to be with people, and loneliness is a psychologically painful experience that has been shown to undermine our health.”
While not as well known as the other factors, BDNF plays a major role in memory formation and creating synapses in the brain. However, it decreases in availability as a person ages—and is especially low among people with dementia.
“Past research has established that various events and circumstances can actually influence its level,” Simons said. “Studies have shown that something as simple as drinking coffee can lead to lower rates of Alzheimer’s.”
Importantly, however, exposure to stress and adversity has been shown to dramatically reduce BDNF—those who live high-stress lifestyles are at greater risk for cognitive decline later in life.
Simons has dedicated over 25 years of his career to studying this group of Black Americans as they progress through the life course. Over the next few years, Simons and his team hope to identify additional factors that explain the elevated risk for dementia seen among Black Americans.
They recently received funding from the National Institute of Aging to perform blood-based tests for defining features of Alzheimer’s disease. They will focus on how factors like racial discrimination, economic hardship and community disorder contribute to Alzheimer’s and related dementias.
This study, titled “Changes in Loneliness, BDNF and Biological Aging Predict Trajectories in a Blood-Based Epigenetic Measure of Cortical Aging: A Study of Older Black Americans,” was published in the 2023 issue of “Genes,” a journal from the Molecular Diversity Preservation International. Mei Ling Ong (UGA Center for Family Research), Man-Kit Lei (UGA Department of Sociology), Steven Beach (UGA Department of Psychology), Yue Zhang (UGA Department of Sociology), Robert Philibert (University of Iowa Department of Psychiatry) and Michelle Mielke (Wake Forest Department of Epidemiology and Prevention) were co-authors on the publication.