Temperature variability and increasing exposure to airborne pollutants — both consequences of climate change — can worsen disease symptoms and risk relapses in people with multiple sclerosis (MS), according to a recent review study.
Unwanted effects of environmental change were also linked to a number of other neurological conditions, including stroke, dementia, migraine, and Parkinson’s disease.
“Climate change poses many challenges for humanity, some of which are not well-studied,” Andrew Dhawan, MD, PhD, a neurology resident at the Cleveland Clinic in Ohio and the study’s senior author, said in an American Academy of Neurology press release.
“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,” Dhawan added.
Review of 364 studies into temperature, disease and pollution changes since 1990
The study, “Impacts of Climate Change and Air Pollution on Neurologic Health, Disease, and Practice: A Scoping Review,” was recently published in the journal Neurology.
With each passing year, global temperatures continue to rise, leading to weather extremes like floods and wildfires, poorer air quality, and expanded geographical regions and seasons in which infectious diseases thrive.
Scientists warn that climate change can also affect human health in ways that include greater food and water insecurity, and a higher risk of respiratory illness and infectious disease.
While links between environmental conditions and respiratory and cardiac diseases are well studied, less is known about the effects of climate change on the prevalence and severity of neurological diseases like MS. The researchers noted that, as the planet continues to warm, this will become an increasingly important question.
“As we witness the effects of a warming planet on human health, it is imperative that neurologists anticipate how the epidemiology and incidence of neurologic disease may change,” the researchers wrote.
The scientists conducted a systematic review of studies published between 1990 and 2022 that were related to climate change, pollution, and neurological diseases in adults.
They identified 364 studies, which were grouped into three major themes: extreme weather events and temperature fluctuation (38 articles), emerging neuroinfectious diseases (37 articles), and impact of pollutants (289 studies).
Climate change and disease relapse risk
Temperature fluctuations and extreme weather events were associated with changes in a number of neurological conditions, including symptoms for MS patients. They were also linked to migraine headaches, hospitalizations in dementia patients, and the incidence and severity of stroke.
Likewise, airborne pollutant exposure, or poorer air quality, associated with an increased risk of an MS relapse. This was particularly true for a type of pollutant called fine particulate matter (PM2.5) — particles less than 2.5 micrometers in diameter and carried in smoke, soot, aerosols, mould, dander, and the like — and nitrates.
Exposure to these pollutants also linked with stroke incidence and severity, headaches, dementia risk, and Parkinson’s.
Warming global temperatures were seen to favor the spread of tick- and mosquito-borne neuroinfectious diseases like the West Nile virus, meningococcal meningitis, and tick-borne encephalitis.
Findings overall highlight a growing impact of climate change on neurologic health.
The researchers noted, however, that the studies were conducted largely in resource-rich geographical areas. Findings might differ in areas with fewer resources, where the effects of climate change on human health may be even more pronounced, they wrote.
Based on their findings, the researchers noted three priorities for future research: mitigating the spread of neuroinfectious disease, understanding how airborne pollutants affect the nervous system, and improving neurological care within a changing environment.
Potential impacts of climate change that weren’t evaluated in the study also warrant investigation, the researchers noted.
“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.
In response to the rising global temperatures, more than 22o medical journals published a joint editorial in 2021 calling for “urgent, society-wide changes” that will prevent average global temperatures from rising by more than 1.5 degrees Celsius before 2100.
Such actions could help to slow environmental degradation and protect neurologic, and overall, human health.