Global Warming and Neurological Practice: Systematic Review

Abstract

BackgroundClimate change, including global warming, is expected to cause poorer global health and a rise in the number of environmental refugees. As neurological disorders account for a major share of worldwide morbidity and mortality, climate change and global warming are also destined to alter neurological practice; however, to what extent and by which mechanisms is unknown. We aimed to collect the available information on the effects of ambient temperatures and human migration on the epidemiological and clinical manifestations of major neurological disorders.MethodsWe searched PubMed and Scopus from January 1, 2000 to November 30, 2020 for human studies published in English addressing the influence of ambient temperatures and human migration on Alzheimer’s and non-Alzheimer’s dementia, epilepsy, headache and migraine, multiple sclerosis, Parkinson’s disease, stroke, and tick-borne encephalitis (as a model disease for neuroinfections). The protocol was pre-registered at PROSPERO (2020 CRD42020147543).Results101 studies met inclusion criteria, but we were unable to identify a single study addressing how global warming and human migration will change neurological practice. Still, extracted data suggested multiple ways by which these aspects might alter neurological morbidity and mortality in the future.ConclusionSignificant heterogeneity exists across studies with respect to methodology, outcome measures, control of confounders and study design, but there is enough evidence to suggest climate change will affect the neurological practice of all major neurological disorders. Adequately designed studies to address this issue are urgently needed, which will require concerted efforts from the neurological community.

Climate change and neurodegenerative diseases

“…In humans, environmental hyperthermia (50°C) has been shown to impair functional connectivity of the brain, with alterations in cognitive and work performance (Sun et al, 2013), as well as in short-term visual memory (Jiang et al, 2013). Ten studies investigated the effects of high environmental temperatures on demented patients (Wei, 2019;Peinkhofer et al, 2020): in 8 of them enhanced temperatures were associated with worsening of symptoms (including agitation) and increased rates of hospitalization and mortality. Two studies evaluated the effects of high temperatures on PD patients (Zanobetti et al, 2013;Linares, 2016).…”

“…An improved understanding of altered pathways and biomarkers during global warming exposure will contribute to the identification of effective prevention and control measures in patients with neurological diseases, and particularly with neurodegenerative diseases, where a likely genetic predisposition to abiotrophy can be associated with an acquired damage resulting from chronic exposure to heat (Peinkhofer, et al, 2020). Unfortunately, how heat exposure can directly modulate human neuronal pathways is still far to be understood.…”