Dementia rates to rise in Black populations disproportionately. From Scope, the blog of the Yale Scientific Magazine.
Our deepening understanding of the human body and advances in technology result in longer, healthier lives for most. However, some people may be more susceptible to conditions that develop with age, such as dementia. Dementia is an age-related decline in cognitive function. Though it was once an uncommon condition, dementia is now the leading cause of disability among the growing elderly population, affecting over six million individuals in America. The most frightening part of dementia is not only its ability to affect memory, reasoning, and behaviors, but rather its irreversibility. Though there are therapies and treatments to slow its progression down, there is no cure.
A recent paper in Nature Medicine compiled three decades of dementia data to determine contemporary estimates of lifetime risk of dementia across groups of people of different races, sexes, and genetic compositions. Senior author Josef Coresh, the director of the Optimal Aging Institute at the New York University Grossman School of Medicine, emphasized the importance of this updated understanding of the risk of dementia.
Participants entered the study with no symptoms of dementia at fifty-five years old. The probability that an individual will develop dementia at some point in their lifetime is around forty-two percent, so many of the participants eventually developed dementia. By analyzing which of the participants developed dementia and which did not, the researchers were able to analyze the changes in the lifetime risk of dementia for groups determined by various genes. The population subgroups with notable results were Black adults and carriers of the gene Apolipoprotein E (APOE) ε4.
APOE ε4 is anAPOE gene variant whose presence leads to a build-up of plaque in the brain. Accordingly, starting at age seventy, participants in the study with two copies of APOE ε4 had a higher lifetime risk of dementia—fifty-nine percent, compared to thirty-nine percent for participants without the gene.
Though there are differences between sexes for lifetime risk, these differences emerge at around age eighty-five. Differences between races, however, emerged a decade earlier, at around seventy-five years. This disparity occurred regardless of whether the participant had APOE ε4 or not. The lifetime risk of dementia for Black adults was forty-four percent, compared to white adults at forty-one percent, and Black adults also generally experienced earlier onset dementia. Researchers speculate that socioeconomic factors of largely Black communities serve a role in the rising risk of dementia. The Black participants in this study were predominantly from Jackson, Mississippi. “They tended to have lower education, and they tended to have more cardiovascular risk factors,” Coresh said. These cardiovascular risk factors have long been considered preventable, yet they remain disproportionately prevalent in marginalized communities. “And it’s important to realize [that] this cohort—many of them are in their eighties now, and [they] grew up during a time of more active segregation,” Coresh said.
This research produced estimates of lifetime dementia risk that were up to double previous estimates. With these updates, the researchers could piece together that the vascular basis and neurodegenerative basis of dementia were highly connected. “Now we’re beginning to piece this together that the same strategies of lowering blood pressure, avoiding diabetes, physical activity, and sleep are going to be helpful for dementia […] We now understand that the risk of dementia is modifiable,” Coresh said.
For such a devastating, widespread condition as dementia, any measure of prevention is critical. However, for Black populations that are socioeconomically restricted from accessing preventative measures, there is a need for structural changes. Limited access to education, nutrition, and treatments following diagnoses are heavy burdens to bear, and everyone has a right to proper care.