Impacts of Climate Change and Air Pollution on Neurologic Health, Disease, and Practice: A Scoping Review

Abstract

Background and objectives: Although the international community collectively seeks to reduce global temperature rise to less than 1.5°C before 2100, irreversible environmental changes have already occurred, and as the planet warms, these changes will continue to occur. 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. In this review, we organized our analysis around 3 key themes related to climate change and neurologic health: extreme weather events and temperature fluctuations, emerging neuroinfectious diseases, and pollutant impacts. Across each of these themes, we appraised and reviewed recent literature relevant to neurologic disease and practice.

Methods: Studies were identified using search terms relating to climate change, pollutants, and neurologic disease in PubMed, OVID MEDLINE, EMBASE, PsycInfo, and gray literature. Studies published between 1990 and 2022 were included if they pertained to human incidence or prevalence of disease, were in English, and were relevant to neurologic disease.

Results: We identified a total of 364 articles, grouped into the 3 key themes of our study: extreme weather events and temperature fluctuations (38 studies), emerging neuroinfectious diseases (37 studies), and pollutant impacts (289 studies). The included studies highlighted the relationships between neurologic symptom exacerbation and temperature variability, tick-borne infections and warming climates, and airborne pollutants and cerebrovascular disease incidence and severity.

Discussion: Temperature extremes and variability both associated with stroke incidence and severity, migraine headaches, hospitalization in patients with dementia, and multiple sclerosis exacerbations. Exposure to airborne pollutants, especially PM2.5 and nitrates, associated with stroke incidence and severity, headaches, dementia risk, Parkinson disease, and MS exacerbation. Climate change has demonstrably expanded favorable conditions for zoonotic diseases beyond traditional borders and poses the risk of disease in new, susceptible populations. Articles were biased toward resource-rich regions, suggesting a discordance between where research occurs and where changes are most acute. As such, 3 key priorities emerged for further study: neuroinfectious 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.

Figure 1. PRISMA Diagram Depicting the Selection Process for Studies Included in This Scoping Review

Figure 2. Neuroinfectious Diseases Studied by Location

Map depicts the number and types of reports examining neuroinfectious diseases stratified by location. 10 reports were published from North America, 14 reports from Europe, 5 reports from Africa, 8 reports from Asia, and 1 report from Australia. Abbreviations: JEV = Japanese encephalitis virus; TBE = tick-borne encephalitis.

Figure 3. Relationships Between Pollutants and Identified Neurologic Links

Sankey diagram depicting inter-relationships between pollutant exposure (left) and neurologic outcome (right). PET refers to positron emission tomography. TIA refers to transient ischemic attack. Abbreviations: MS = multiple sclerosis; PD = Parkinson disease.