Incidence and Severity of Neurologic Diseases Worsening Due to Air Pollution, Climate Change

Exposure to airborne pollutants and temperature extremes and variability were associated with incidence and severity of several neurologic diseases and stroke. Climate change may also increase risk for emerging neuroinfectious diseases carried by animals and insects, such as West Nile virus, among new, susceptible populations. Findings were published today in Neurology.

Growing literature on the health-related impact of climate change and air pollution has demonstrated increased risks of mental health disorders, dermatologic conditions, and cardiovascular disease, among other conditions. However, researchers note that the influence that these climate effects have on risk of neurologic disease and individuals with these conditions are less well characterized.

Prior research has demonstrated that air pollution, specifically exposure to fine particulate matter (PM_2.5), was significantly associated with an increased risk of hospital admissions for neurological disorders, such as Parkinson disease (PD) and Alzheimer disease. Other findings have shown that long-term exposure to PM_2.5 may significantly increase risk of dementia.

Amid increasing extreme weather events attributed to climate change, over 220 medical journals published a joint editorial in September 2021 calling for urgent action to keep average global temperature increases below 1.5 degrees Celsius before 2100, as well as halt the destruction of nature and protect health. Although, irreversible environmental changes have already occurred, said the study authors, and as the planet warms, these changes will continue to occur.

“As the warming of our planet becomes increasingly apparent, there is an urgency to understand the impact of increasing temperatures on neurologic health in order to mitigate the effects on morbidity, mortality, and the burden on health care workers and health systems,” said the study authors.

“Neurologists and neuroscientists have a duty not only to critically examine these potential changes, but also to quantify their impact to better prepare patients and health care systems.”

They conducted a scoping review to increase comprehension on 3 key themes related to climate change and neurologic health: extreme weather events and temperature fluctuations, emerging neuroinfectious diseases, and pollutant impacts.

A total of 364 studies published between 1990 and 2022 within PubMed, OVID MEDLINE, Embase, PsycInfo, and grey literature databases were included in the analysis and grouped into the 3 key themes of the study; extreme weather events and temperature fluctuations (38 studies), emerging neuroinfectious diseases (37 studies), and pollutant impacts (289 studies).

Eligible studies were published between 1990 and 2022, pertained to human incidence or prevalence of disease, were in English, and were relevant to neurologic disease. Additionally, studies addressed adult neurological diseases only, whereas literature on neuropediatric conditions and outcomes were excluded.

Findings of the review highlighted the relationships between temperature variability and worsening neurologic symptoms, warming climates and tick- and mosquito-borne infections, as well as airborne pollutants and cerebrovascular disease rate and severity:

• Extreme weather events and temperature fluctuations were associated with stroke incidence and severity, migraine headaches, hospitalization in patients with dementia, and worsening multiple sclerosis (MS)
• Exposure to airborne pollutants, especially PM_2.5 and nitrates, were associated with stroke incidence and severity, headaches, dementia risk, PD, and MS exacerbation
• Climate change was indicated to expand favorable conditions for emerging neuroinfectious diseases beyond traditional geographic areas, including West Nile virus, meningococcal meningitis, and tick-borne encephalitis

As the studies were conducted in resource-rich regions of the world, researchers acknowledged that results may not be generalizable for regions with fewer resources where such climate effects may be even more pronounced.

“While our review did not identify any articles related to effects on neurologic health from food and water insecurity, these are clearly linked to neurologic health and climate change,” noted researchers. “Akin to social determinants of health, a changing climate and environmental pollutants cannot be overlooked as mediators of disease burden.”

They concluded that further research is warranted on neuroinfectious disease risk mitigation, how air pollution affects the nervous system, and how to improve delivery of neurologic care in the face of climate-related disruptions.

“Our goal is to inspire action through a collective voice among neurologists and health care workers to elicit true change in mitigating the effects of the climate crisis.”

Reference

Louis S, Carlson AK, Suresh A, et al. Impacts of climate change and air pollution on neurologic health, disease, and practice: A scoping review. Neurology. Published online November 16, 2022. doi:10.1212/WNL.0000000000201630