Is dirty air driving up dementia rates?

Antonella Zanobetti.

Veasey Conway/Harvard Staff Photographer

Health
Is dirty air driving up dementia rates?

Federal funding cuts halt 3 studies exploring how pollution and heat affect the brain and heart

Liz Mineo

Harvard Staff Writer

August 4, 2025 4 min read

Antonella Zanobetti was conducting groundbreaking research to examine links between exposure to environmental factors, such as pollution and heat, and deadly neurological and cardiovascular diseases. But three of her studies came to a halt with the Trump administration’s mass cancellation of Harvard research grants in May.

Preliminary evidence suggests air pollution harms the brain, said Zanobetti, an environmental epidemiologist and principal research scientist at the T.H. Chan School of Public Health. She had hoped that her studies would raise awareness of potential links between exposure and increased risk of dementia, as well as explore the protective effects of modifiable risk factors such as green space.

“It’s crucial to finish all the work that we are doing,” said Zanobetti, who led a team of researchers in 2020 to conduct the first national study on air pollution’s effect on Alzheimer’s and Parkinson’s. “We need to understand the factors that can impact hospitalization for neurological disorders. The high prevalence of neurodegenerative diseases is a matter of public health.”

Fueled by aging and industrialization, neurological disorders are surging around the country and the world. Alzheimer’s disease is the sixth leading cause of death in the U.S., and the death rates for Parkinson’s are rising fast. The number of people globally with Parkinson’s is projected to reach more than 12 million by 2040.

“It’s important to understand the role of environmental exposures on neurological disorders to help develop public health policies.”

For one of Zanobetti’s halted studies, her team was analyzing Medicare and Medicaid claims to estimate how long-term exposure to air pollution may increase hospitalizations for Alzheimer’s and related dementias. “We wanted to assess whether air pollution exposure increases risk of mortality and/or hastens rehospitalization,” she said.

Collecting the data was challenging because when patients with Alzheimer’s or Parkinson’s are hospitalized, their neurodegenerative disease is often not the main reason. “It could be a stroke or a fall,” said Zanobetti. “We were in the middle of developing methods to overcome statistical challenges, including outcome misclassification, in addition to studying the impact of heat on hospitalizations.”

Another study, co-led by Danielle Braun, examining the effect of heat and other environmental exposures on hospitalizations for Parkinson’s was supposed to have two more years of funding when it was canceled.

“We were in the middle of looking at the effects of high temperature and other air pollutants on Parkinson’s hospitalization,” said Zanobetti. “We wanted to estimate the chronic and acute effects of multiple environmental exposures to understand the impact of air pollution, heat, or other exposure on Parkinson’s hospitalizations.”

Zanobetti had a third grant terminated. Co-led by Petros Koutrakis, the study was to be the first to provide evidence of the effects of particle radioactivity on heart disease, which is the leading cause of death in the U.S.

Particulate matter, or tiny particles of air pollutants, can be inhaled and reach the lungs, the heart, and the brain, said Zanobetti. Particle radioactivity is caused by radionuclides in the air that attach to ambient fine-particle pollution and, after inhalation, release ionizing radiation inside the body.

The Environmental Protection Agency has used previous research by Zanobetti and her team on particulate matter’s impact of on health to lower National Ambient Air Quality Standards for fine particulate matter in order to reduce health risks linked to air pollution. Last year, her work and that of other T.H. Chan School of Public Health researchers helped establish more rigorous federal regulations on particulate air pollution.

Overall, Zanobetti’s three canceled grants sought to provide scientific evidence of the links between environmental factors and Alzheimer’s, Parkinson’s, and heart disease to inform the development of policies that would improve air quality and protect public health, she said.

“It’s important to understand the role of environmental exposures on neurological disorders to help develop public health policies,” said Zanobetti. “It’s really heartbreaking to see that everything we worked for has been stopped. There is so much to discover, so much to learn, and we cannot do it.”