A growing body of evidence suggests that certain modifiable health conditions, such as high blood pressure, obesity, and type 2 diabetes, can make a person more likely to develop dementia. But a new study published in the journal PLoS One finds that these risk factors aren’t “one-size-fits-all” and may impact people differently depending on their race or ethnicity.
Investigators found that not only do a higher proportion of Black and South Asian adults experience certain dementia risk factors compared with white adults, but the impact of certain risk factors may be greater.
“This is a really important finding that has not been identified before,” says lead author Naaheed Mukadam, MD, PhD, researcher at University College London in England.
Dementia Is a Growing Concern as Populations Age
Dementia is the loss of cognitive functioning, which includes things like the ability to think, remember, and reason to the point where it interferes with a person’s daily life, according to the National Institute on Aging.
As populations of many countries, including the United States, skew older and older, dementia is expected to become an increasing problem. A study published in January 2022 in The Lancet Public Health projected that the number of adults living with some form of dementia in the United States will double by 2050, rising from around 5 to 10 million.
But experts also believe there are actions people can take to reduce their dementia risk that could theoretically prevent around 40 percent of cases, according to a report published in 2020 by the Lancet Commission.
The problem is, many studies on modifiable risk factors for dementia have only been conducted with white adults of European descent, according to the authors. “It’s crucial that we recognize that prevention and management of health conditions like dementia need to be tailored to the individual and that the same approach may not be suitable for everyone,” says Dr. Mukadam.
Hypertension-Dementia Link Was Strongest in Black and South Asian Adults
To examine risk factors and dementia onset in a diverse group, researchers used anonymized data from U.K. primary care records from 1997 to 2018, assessing close to 900,000 adults.
In those two decades, more than 12 percent of the study population developed dementia — 16 percent of white adults, almost 9 percent of South Asians (Asian Bangladeshi, Indian, Pakistani), 12 percent of Black adults (Black British, Black African, Black Caribbean), and almost 10 percent of adults from other ethnic groups, which included Chinese, Arab, and other Asian.
The researchers scrutinized the data to see which study subjects had dementia risk factors including hypertension, obesity, hearing loss, diabetes, smoking, depression, alcohol excess, dyslipidemia (high total cholesterol), low levels of HDL (“good” cholesterol), high levels of LDL (“bad” cholesterol), sleep disorders, and traumatic brain injury.
The researchers found that certain risk factors were often associated with a higher risk of dementia in Black and South Asian people than in white people, particularly risk factors related to cardiovascular health.
Other key findings included the following:
- After adjusting for factors such as age; sex; and education, income, and neighborhood, hypertension (high blood pressure) was linked with a higher risk of dementia in Black people compared with white people.
- Hypertension, obesity, diabetes, low HDL, and sleep disorders conferred a higher risk of dementia in South Asian people.
- Compared with the effects in white people, hypertension had 1.57 times more impact on dementia risk in South Asian people and 1.18 times more impact in Black people.
These findings may explain previous findings of greater susceptibility, earlier age of dementia onset, and shorter survival after dementia diagnosis in minority ethnic groups, the authors wrote.
Future Research Could Focus on the ‘Why’ Behind Racial and Ethnic Differences
This study is significant both from a social justice and a scientific standpoint, says Kyan Younes, MD, clinical assistant professor and researcher at Stanford Medicine in California, who was not involved in this research.
“For any scientist, you want to strive for your data to be generalizable to the entire population. Without the inclusion of underserved minorities, there is no good science,” he says.
This study is a good starting point to highlight areas that dementia researchers should be focusing on, says Mukadam.
The next step is understanding why these differences exist, says Dr. Younes: “There are multiple factors at play that could potentially increase risk, including exposures, access to healthcare, and health literacy, to name just a few.”
Future research focused on the “why” behind the racial and ethnic differences can be used to tailor prevention efforts and make them more equitable, says Mukadam.
Ask Your Doctor About Your Risk Factors for Dementia
These findings suggest that patients should ask their healthcare provider about risk factors for dementia and if they have any, says Albert Lai, MD, PhD, neurologist and researcher at UCLA Health in Los Angeles, who was not involved in this study.
“Patients should also consider asking their doctors whether more aggressive treatment or surveillance for dementia is warranted,” he says.
Mukadam recommends thinking about brain health along with cardiovascular health. “It is worth getting hearing and blood pressure checked regularly and ensuring we are incorporating healthy habits into our lives at any age, but particularly once we are in midlife,” she says.