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11-16-2022

Climate change may worsen neurologic conditions

Climate change holds many challenges for humanity – apart from the obvious ones like increasing temperatures, extreme weather events and sea level rise, that is. We probably haven’t even thought about some of these challenges, but they will become part of our lives as Earth’s ecosystems respond to the warmer conditions. 

A study published in Neurology®, the medical journal of the American Academy of Neurology, has now investigated whether climate change and pollution are affecting the extent and severity of neurologic diseases, such as headaches and migraines, strokes, dementia, multiple sclerosis (MS) and Parkinson’s disease. The authors of the review searched through published literature to find studies on climate change, pollutants, temperature extremes and neurologic diseases between 1990 and 2022. 

The experts identified 364 relevant studies in three categories, including 289 studies on the impact of pollution, 38 studies on extreme weather events and temperature fluctuations and 37 studies on emerging neuroinfectious diseases. Only studies involving adults were included. 

“Although the international community seeks to reduce global temperature rise to under 2.7ºF (1.5oC) before 2100, irreversible environmental changes have already occurred, and as the planet warms these changes will continue to occur,” said Dr. Andrew Dhawan of Cleveland Clinic in Ohio, who is a member of 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.”

The results of the investigation showed that extreme weather events and temperature fluctuations were indeed associated with stroke incidence and severity, as well as with migraine headaches, increased hospitalizations in dementia patients and worsening of MS symptoms. Furthermore, changing climatic conditions have led to the expansion of favorable environments for emerging neuroinfections diseases like West Nile virus, meningococcal meningitis and tick-borne encephalitis. These diseases, carried by insects and other animals, now pose a risk of disease to human populations. 

Fine particulate matter, also known as PM 2.5, is a common air pollutant and the review found that exposure to this type of airborne pollutant, along with exposure to nitrates, is associated with increased stroke incidence and severity, as well as with headaches, dementia risk, Parkinson’s disease, and worsening of MS symptoms. 

These findings highlight the relationships between temperature variability and worsening neurologic symptoms, between warming climates and tick- and mosquito-borne infections, as well as between airborne pollutants and cerebrovascular disease rate and severity.

“Climate change poses many challenges for humanity, some of which are not well-studied,” said Dr. Dhawan. “For example, 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. 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.”

Since most of the research publications considered in this review collected data in resource-rich regions of the world, the results may not be applicable in regions with fewer resources, where such changes may be even more likely to occur. Despite this limitation, it is clear that changing climatic conditions and air pollution are likely to exacerbate neurologic conditions in human sufferers in the future.

By Alison Bosman, Earth.com Staff Writer

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