As the Earth continues to warm at an alarming rate, the effects of climate change on human health are becoming increasingly evident. While much attention has been given to the impact of rising temperatures on physical health, a group of experts from University College London (UCL) is sounding the alarm about the potentially devastating consequences of climate change on brain health.
In a comprehensive review published in the journal Lancet Neurology, researchers examined the current scientific literature on the relationship between climate change and a wide range of neurological and psychiatric disorders, including stroke, migraine, dementia, epilepsy, multiple sclerosis, and mental health conditions such as depression and anxiety.
The findings are sobering: the incidence, prevalence, and severity of many nervous system disorders appear to be significantly impacted by rising temperatures and other climate-related factors. Scientists warn that without urgent action to curb greenhouse gas emissions and adapt to the changing climate, the global burden of these conditions is likely to increase dramatically in the coming decades.
One of the most striking findings of the review is the complex and often bimodal relationship between temperature and brain health. While some studies have found an increased risk of stroke, epilepsy, and other conditions during heatwaves and periods of extreme heat, others have noted a similar uptick in hospitalizations and emergency department visits during cold spells and temperature drops.
“There is clear evidence for an impact of the climate on some brain conditions, especially stroke and infections of the nervous system,” says lead study author Sanjay Sisodiya, professor at UCL Queen Square Institute of Neurology. “The climatic variation that was shown to have an effect on brain diseases included extremes of temperature (both low and high), and greater temperature variation throughout the course of day – especially when these measures were seasonally unusual.”
Researchers suggest that this apparent paradox may be due in part to the fact that the human body is adapted to function within a relatively narrow range of temperatures, and that any deviation from this “Goldilocks zone” can disrupt the delicate balance of the nervous system. Additionally, many neurological disorders are characterized by a heightened sensitivity to temperature fluctuations, meaning that even small changes in ambient temperature can trigger or exacerbate symptoms.
“Nighttime temperatures may be particularly important, as higher temperatures through the night can disrupt sleep. Poor sleep is known to aggravate a number of brain conditions,” explains Sisodiya.
Beyond the direct effects of temperature on brain function, the review also highlights the myriad indirect ways in which climate change can impact neurological health. For example, rising temperatures and changing precipitation patterns are expected to alter the distribution and abundance of disease-carrying insects and other vectors, potentially exposing more people to neurological infections such as meningitis, encephalitis, and Zika virus.
Moreover, researchers note that the mental health consequences of climate change are likely to be far-reaching and long-lasting. Extreme weather events such as hurricanes, wildfires, and floods can cause acute psychological distress and trauma, while the chronic stress of living in a world increasingly destabilized by climate change may contribute to the development of anxiety, depression, and other mental health disorders.
“The whole concept of climate anxiety is an added, potentially weighty, influence: many brain conditions are associated with higher risk of psychiatric disorders, including anxiety, and such multimorbidities can further complicate impacts of climate change and the adaptations necessary to preserve health. But there are actions we can and should take now,” notes Sisodiya.
Despite the grim outlook, researchers emphasize that there is still time to act to mitigate the worst impacts of climate change on brain health. They call for urgent action to reduce greenhouse gas emissions and transition to a low-carbon economy, as well as increased investment in research to better understand the complex interplay between climate and neurological disorders.
At the individual level, researchers recommend a number of strategies for protecting brain health in a warming world, including staying hydrated, seeking out air-conditioned spaces during heatwaves, and being mindful of the potential for temperature-related symptom flare-ups. They also stress the importance of building resilience and social support networks to help cope with the mental health impacts of climate change.
