Where You Live Could Increase Your Dementia Risk

A new study led by Duke University has found a link between people who live in poorer neighborhoods and an increased risk of dementia.

A total of 50 million people globally are living with Alzheimer’s disease and related dementias. This number is expected to reach 150 million in 30 years as the global population ages. The neurological disorder affects people’s memories and cognitive skills. While dementia is typically seen in older populations, the new Duke University study found that where you live can affect your dementia risk and how early you get the disorder.

The Duke study, published in Alzheimer’s & Dementia, a journal from the Alzheimer’s Association, was led by clinical neuropsychologist Aaron Reuben. He worked with Duke University colleagues Dr. Avshalom Caspi and Dr. Terrie E. Moffitt, as well as collaborators from the University of Michigan, Michigan State University and New Zealand’s University of Otago, and the University of Auckland.

The team looked at 1,695,447 individuals from the ages of 31 to 90. The subjects of the study were born in New Zealand between 1929 and 1968 and lived in the country for any time between July 1999 and June 2019. Populations from the United Kingdom and the United States were also analyzed.

Reuben and his team looked at the subjects’ residential neighborhood socioeconomic status using census data such as rates of unemployment, education and home ownership.

The researchers found that individuals living in the most disadvantaged areas had a 43 percent increased risk of developing dementia over 20 years of observation.

Reuben told Newsweek on Thursday that similar studies have been carried out in the U.S. but using samples of people followed for short time spans, or the medical record reviews of, for example, members of the Veterans Affairs health system.

“We are looking at a highly robust phenomenon that appears to show up wherever we look—at least in industrialized countries with similar development patterns, like the U.S., U.K., Australia and New Zealand,” Reuben said.

Reuben’s team also looked at data from the Dunedin Study, which documented 938 New Zealanders’ social backgrounds and psychological health since birth. The participants were born between April 1972 and March 1973 in Dunedin, New Zealand.

Reuben and his colleagues found that Dunedin Study participants living in disadvantaged neighborhoods had poorer brain health as early as age 45, regardless of their personal income or education. Poorer brain health was measured by factors such as fewer or smaller nerve cells in the brain’s information processing areas and less efficient communication between cells across the brain.

There were some limitations of the study, including the observational nature of it and the fact that it cannot establish causation. Also, it is important to note that neighborhood disadvantage was only assessed during adulthood, which means it is unclear if neighborhood-brain-integrity associations could be present earlier in life.

Reuben told Newsweek: “As you likely know, the global burden of dementia is increasing and going to increase until we find effective ways to prevent, treat or delay the disease.

“What our study shows is, dementia is a disease that is geographically and socially patterned—meaning if you want to target studies, treatments and preventive efforts to reach the people at greatest risk, you really need to consider where people are living, not just what their blood pressure report says, or other medical metrics.

“This means we potentially have a much larger arsenal for trying to prevent dementia because we don’t need to wait until someone shows up in a clinic with memory complaints. We can meet them where they live to try and resolve the antecedent risk factors that are operating at a community level.”

Reuben also mentioned the next step in his research.

“Perhaps making safe, walkable streets could fight dementia. Perhaps farmer’s markets and neighborhood parks are part of our healthcare system in a way we had not previously imagined,” he said. “Those are the next things we would like to study—what components of disadvantaged neighborhoods are driving this increased risk if the association is causal, and what components of advantaged neighborhoods are driving down risk?”

Experts Weigh In

June Andrews, a registered nurse from the U.K. who specializes in dementia studies, told Newsweek that “It has been known for some time that there is a link between lifestyle, factors and opportunities and risk of dementia.

“It used to be that doctors in areas of social deprivation told me that they did not meet many people with dementia because nobody lived long enough to have this disease, which is more prevalent in people in later life. The exception they would mention was alcohol-related brain damage and brain damage from head injuries. Both of [these] are contributory factors for dementia.”

Andrews explained various environmental and lifestyle factors that could play a role in dementia risk.

“More recent studies into air quality suggest that this plays a more important role than we previously thought,” she said. “People in low economic conditions are much more likely to live in the sort of areas where they do not have access to gardens or a park and therefore the quality of the air that they breathe 24 hours a day is poor.

“The lifestyle factors which would delay the onset of dementia or reduce the symptoms when a person is affected are those which are easier to access if you are an affluent person. Staying on longer in education, having the time and leisure to take exercise, eating a good diet, all of these things are easier if you have resources to look after yourself.”

Dr. Charles B. Hall, a professor at the Albert Einstein College of Medicine in New York who studies aging and dementia, also discussed how air quality may impact dementia risk.

Hall told Newsweek that the study shows that “there have to be factors beyond socioeconomic status that explain the effects the researchers found. The researchers propose a number of candidates for investigation and many researchers, including our team at Einstein, are examining them along with other factors related to neighborhood here in the Bronx.

“There is biological plausibility for many such factors (including air pollution). A lack of individual level risk factor exposure data has made it difficult to quantify accurately the contribution of these risks to the burden of dementia, but we are now addressing that with new technology.”

Update 3/14/24, 2:11 p.m. ET: This article has been updated with comment from Dr. Charles B. Hall.