Air Pollution Due to Climate Change May Raise Parkinson’s Risk

Study looks into likely effects of environmental degradation on neurologic health

Vanda Pinto, PhD avatar

by Vanda Pinto, PhD |

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Exposure to airborne pollutants, which is rising as a result of climate change, appears to increase the risk of Parkinson’s disease, according to a review study into how a changing environment can affect human health.

Air pollutants and other aspects of climate change also were found to associate with an occurrence or worsening of other neurologic diseases, including dementia and multiple sclerosis (MS).

“Although the international community seeks to reduce global temperature rise to under 2.7 ºF before 2100, irreversible environmental changes have already occurred, and as the planet warms these changes will continue to occur,” Andrew Dhawan, MD, PhD, the study’s senior author, said in a press release from the American Academy of Neurology.

“As we witness the effects of a warming planet on human health, it is imperative that neurologists anticipate how neurologic disease may change,” added Dhawan, who is with a neurologist at the Cleveland Clinic’s Neurology Institute, in Ohio, and a member of the American Academy of Neurology.

The review study, “Impacts of Climate Change and Air Pollution on Neurologic Health, Disease, and Practice: A Scoping Review,” was published in the journal Neurology.

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Environmental factors like air pollution linked to Parkinson’s

Although the precise cause of Parkinson’s is still unknown, many researchers believe it develops as a result of a combination of genetic and environmental factors. Some studies have linked ingested and inhaled environmental pollutants with the neurodegenerative disease.

Small particles from air pollution are known to trigger biological processes such as inflammation, cell damage, and the destruction of nerve cells, which occur in several neurological disorders.

An example of a common air pollutant is nitrogen dioxide. This gas, emitted from motor vehicles and tobacco, causes several harmful effects on the lungs, including airway inflammation, coughing, and wheezing.

How climate change might influence the prevalence and severity of neurological diseases like Parkinson’s, however, remains largely unclear.

Dhawan and colleagues at Cleveland Clinic’s Neurology Institute and Lerner College of Medicine systemically reviewed published studies between 1990 and 2022 that analyzed potential links between climate change and neurologic disease frequency and severity in adults.

They focused on three key themes related to climate change and neurologic health: extreme weather events and temperature fluctuations, emerging neuroinfectious diseases, and pollutants.

A total of 364 publications were identified and grouped into the three key themes: 289 studies on the impact of pollutants, 38 on extreme weather events and temperature fluctuations, and 37 studies on emerging neuroinfectious diseases.

These studies focused on the links between symptom worsening and temperature fluctuation, tick-borne infections and warming temperatures, and airborne pollutants and the frequency and severity of cerebrovascular diseases — those that affect blood flow and the blood vessels in the brain.

Fire particulate matter, like that in smoke and smog, of particular concern

Extreme and fluctuating temperatures both linked to stroke incidence and severity, migraine headaches, hospitalizations among people with dementia, and a worsening of MS symptoms, results showed.

Exposure to airborne pollutants, namely fine particulate matter (PM2.5) and nitrates, also were associated with stroke frequency and severity, headaches, dementia risk, Parkinson’s, and MS worsening. PM2.5 are particles less than 2.5 micrometers in diameter, consisting of smoke, soot, aerosols, mold spores, dander, and the like. Nitrates are formed from nitrogen dioxide.

Data also suggested that climate change may provide favorable conditions for tick- and mosquito-borne neuroinfectious diseases such as West Nile virus, meningococcal meningitis, and tick-borne encephalitis to spread beyond their traditional areas.

“Our review did not find any articles related to effects on neurologic health from food and water insecurity, yet these are clearly linked to neurologic health and climate change,” Dhawan said.

“More studies are needed on ways to reduce neuroinfectious disease transmission, how air pollution affects the nervous system, and how to improve delivery of neurologic care in the face of climate-related disruptions,” the neurologist added.

Among their review’s limitations, the researchers noted that included studies were mainly carried out in resource-rich geographical regions. This means its results may not be generalized to regions with fewer resources, where climate change’s impact may be even more pronounced.

“Three key priorities emerged for further study; neuro-infectious disease risk mitigation, understanding the pathophysiology of airborne pollutants on the nervous system, and methods to improve delivery of neurologic care in the face of climate-related disruptions,” the scientists concluded.

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