Black adults at risk for Alzheimer’s disease live in more polluted areas, US study finds
Study of 107 older adults finds that non-white New York and North Carolina residents with mild cognitive impairment reside in places with more environmental injustices than their white peers
IMAGE:
FIRST AUTHOR - ALISA ADHIKARI
view moreCREDIT: DUKE UNIVERSITY
DURHAM, NC – May 16, 2024: A study by Duke and Columbia Universities finds older, non-white adults are more likely to live in areas with higher air pollution and near toxic disposal sites, among or environmental injustices, potentially underlying their cognitive health.
“A lot of money has been spent on understanding the genetics and pathological characterization of Alzheimer's disease,” said P. Murali Doraiswamy, MBBS, FRCP, a professor of psychiatry and behavioral sciences at Duke University’s School of Medicine, and senior author of the study. “But we still don’t have a good way to quantify the dozens of environmental risks for the disease and how they may interact together.”
The results add to a growing area of research exploring the connections between environmental factors and brain health, racial injustices, and aging, and suggests looking at a patient’s address may be just as important for care providers to consider as listening to their heart or ordering a brain scan.
The results were published May 14, 2024 in the Journal of Alzheimer’s Disease Reports.
Location and Brain Health
Where someone lives can influence their brain health. Middle-aged women get a cognitive boost when residing in areas with more trees, flowers, parks and other green spaces, whereas living in poorer neighborhoods with more polluted air elevates risks for and rates of Alzheimer’s disease.
These are piecemeal examples, though.
“An all-encompassing snapshot tying multiple environmental factors and resources available based on where someone lives to neurodegenerative disorders, like Alzheimer's disease, has not been explored as well,” said Alisa Adhikari, a clinical research associate in Dr. Doraiswamy’s lab and the study’s first author.
Race and Place on the Mind
107 participants aged 55 – 95 with mild cognitive impairment living in or around New York City, NY or Durham, NC were recruited to study the effectiveness of computerized cognitive training therapies, such as crossword puzzles and brain games, on slowing dementia progression over 78 weeks.
To get a fuller sense of how place, race, and the mind influence each other, co-author Adaora Nwosu pulled in data from the Center for Disease Control’s Environmental Justice Index (EJI). The EJI provides location-specific information about 36 environmental and social burden indicators such as neighborhood walkability and access to green spaces, diesel exhaust, air, water and noise pollution levels, as well as the likelihood of living in older homes with greater exposure to lead or asbestos.
Non-white participants, mainly Black enrollees, were found to face higher environmental burdens.
“Minorities had greater exposure to ozone, diesel, particulate matter, carcinogenic air toxins, lack of recreation of parks, and proximity to toxic disposal sites,” Adhikari said, which she says explains, in part, the higher environmental burden scores.
Older non-white adults also scored much worse on social vulnerability metrics, such as more likely to live in older homes within poorer neighborhoods, which the authors suggest may be a result of past injustices.
There were no connections found, however, between race, location, and measures of cognitive decline likely due to all participants actively taking medicine and doing brain training exercises to curb neurological symptoms, as part of the study’s original research design.
Analysis of the EJI data also revealed that adults from the New York City site tended to live in areas with markedly higher pollution compared to counterparts in Durham, which may have impacted or accelerated their decline even before enrolling in treatment.
“This was eye-opening for us,” Dr. Doraiswamy said. “We tend to treat all sites and all subjects in a clinical trial as homogeneous with regards to environmental exposures. Moving forward, this type of metric may prove useful to help us better study how environmental exposures impact clinical trial outcomes.”
ZIP Codes as Part of a Checkup
Dr. Doraiswamy described the findings as a “pilot study,” and as such, his team is now planning for a larger, national study with thousands of participants that includes more objective neurodegeneration measurements like MRI brain scans to better assess cognitive health over time.
“The intent is not to substitute for clinical history or a blood test or require this for entry into a research study,” Dr. Doraiswamy said. “It's just that with clinical history, there's no way of measuring objectively what kind of a neighborhood exposures a person has unless you actually go and visit every single patient's home and take measurements with a sensor and so on and so forth.”
Ultimately, the team hopes that this study will spur more collaborations between clinical and environmental researchers to mitigate racial injustices and ensure everyone has access to a brain healthy environment.
JOURNAL
Journal of Alzheimer s Disease Reports
METHOD OF RESEARCH
Meta-analysis
SUBJECT OF RESEARCH
People
ARTICLE TITLE
Characterizing Neighborhood Vulnerabilities in Mild Cognitive Impairment using the Environmental Justice Index
ARTICLE PUBLICATION DATE
17-May-2024
Study suggests that air pollution promotes inflammation in the brain, accelerating cognitive decline and increasing risk of dementia
This is the first study in Denmark showing a link between air pollution and dementia. "The novelty of this study is the very detailed and accurate data that we use," says researcher behind the study.
Results from new study suggests that long-term exposure to air pollution leads to increased risk in dementia in Denmark.
"We also find association with noise, but this seems to be explained by air pollution primarily. Our study is in line with growing international knowledge on this topic." says Professor at Section of Environmental Health Zorana Jovanovic Andersen.
This is an important finding which adds that air pollution, beyond well-known effects on respiratory and cardiovascular system, also has major impacts on our brain, promoting inflammation in the brain, accelerating cognitive decline, and increasing risk of dementia.
"This is the first study in Denmark showing a link between air pollution and dementia. Although air pollution levels in Denmark have been declining and are relatively low, compared of the rest of Europe and world, this study shows that there are still significant and concerning health effects that demand more action and policies towards reduction of air pollution. As we are going to live longer, and more and more people will be diagnosed with dementia, this finding is important as it offer an opportunity to prevent new dementia cases, and ensure more healthy aging, by cleaning up the air we breathe," says Zorana Jovanovic Andersen.
An internationally unique study
The study followed a cohort of nurses for 27 years, from 1993 until 2020.
“This is internationally unique and necessary in regards of the development of dementia which can take many years. Second, the air pollution was estimated for each participant for a total of 41 years (from 1979 until 2020), which is also incredible. Third, we had extensive details about participant’s lifestyle and socio-economics and all our result take them in consideration. The novelty of this study is the very detailed and accurate data that we used,” says Research Assistant from Section of Environmental Health Stéphane Tuffier.
“Nurses with higher physical activity had a lower risk of dementia when exposed to air pollution compared to nurses with less physical activity. This indicates that physical activity might mitigate the adverse effects of air pollution on cognitive decline and risk of dementia,” Tuffier says.
JOURNAL
Alzheimer s & Dementia
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
People
ARTICLE TITLE
Long-term exposure to air pollution and road traffic noise and incidence of dementia in the Danish Nurse Cohort
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