Professor Sanjay Sisodiya on how climate change impacts our neurological health

We all know the feeling of trying to drift off to sleep in the hot weather – the endless tossing and turning as we attempt to get comfortable, kicking off our bedsheets as we try to cool down, throwing open the windows in the hope of the relief of the slightest breeze.

And we also know that the longer a heatwave lasts, the more unable to focus, irritable and exhausted we can feel in our daily lives.

As our planet’s temperature continues to rise at alarming rates, more and more of us will feel the impact of sleepless nights. This may be particularly harmful for people susceptible to some brain disorders, such as stroke and epilepsy.

Professor Sanjay Sisodiya (UCL Queen Square Institute of Neurology), an expert in epilepsy, has been taking a closer look at how climate change impacts our brain health.

Professor Sisodiya says: “Almost every system in the world, both natural and man-made, functions at temperatures that have been stable for a long period of time. This includes the biological systems inside all of us, like our brains.

“Pushed beyond limits of resilience, the brain can malfunction. At a simple level, consider how a heatwave disrupts our sleep, and the impact of disturbed sleep on our health in general, and subsequent cognitive function in particular. My biggest concern is how the brain will fare for all of us - whether we have health conditions or not - as climate change progresses with all its consequences. We need our brains to manage the challenges around us, but what if our brains themselves are affected by those challenges, even for some of the time?”

The existing research around the effects of climate change on brain health is limited. In a recent literature review, published in Nature Reviews Neurology, Professor Sisodiya led a team that examined the data we already have.

His interest in the effect of changing temperatures on the brain originated from his own concerns about our planet.

“My personal concerns about climate change and my experience seeing people with epilepsy in clinic made me think that we had better understand exactly what the consequences might be within my professional sphere of activity - epilepsy - so that we could better prepare for the changes we are experiencing and will see in the future.”

Epilepsy is a condition that affects the brain and causes frequent seizures. It can start at any age and there are many different types. Certain rare severe types of epilepsy, such as some developmental and epileptic encephalopathies, are already known to be aggravated by extreme temperatures. Some people with epilepsy are also more likely to be hospitalised in either very hot and very cold weather and the effects seem to be aggravated further by pollution.

“When we start to change the very environment within which we are living and operating, then we risk also changing many aspects of disease biology, potentially rendering our current understanding wanting and compromising progress in treating these, and other, conditions,” Professor Sisodiya explains, “For example, in epilepsy, high ambient temperatures may exacerbate brain excitability, disrupt sleep, compromise access to, and efficacy of, medications, or bring out their adverse effects, all potentially aggravating seizures and comorbidities.”

In 2020, temperatures reached a staggering 37.8°C in the UK and we experienced three heatwave periods. In a survey by the Epilepsy Society of more than 1,000 people living with epilepsy taken after the first heatwave, 56.1% of people said that their seizures were more frequent and more severe during the extreme temperatures.

For clinicians like Professor Sisodiya, this is worrying.

“We may invent smart, precise, informed new treatments, but what will happen to those approaches when we experience unprecedented environmental challenges, for example with temperatures never before seen?” he asks.

It is clear that more research is needed to help us understand the extent of climate change on brain health.

Professor Sisodiya says: “Most importantly right now, we need to establish who, and which conditions, are most at risk and how best to manage those risks. It may be that some conditions will not be particularly aggravated, for example, by heatwaves – we can then target our attention first to conditions that will be most vulnerable. But eventually we will need to know how worsening environmental conditions will affect brain function in us all.

“We urgently need funding for more research targeted at swiftly understanding the risks posed by climate change to those with existing health conditions, beyond work that is looking at issues at the population level. Climate change has to become part of our daily thinking at all levels, as currently its progress seems inevitable.”

Readjusting our daily habits in response to climate change may be a good way to respond to changing temperatures. A lot can be learnt from countries that already experience extreme climates.

“Such measures are widely available and applicable to us all – such as trying to keep out of the sun during the hottest part of the day in a heatwave, and simple measures such as circulating the air in the room to try to cool down to help us sleep,” Professor Sisodiya says.

Whilst we do need to take action against climate change, Professor Sisodiya says there is no need for alarm in regard to individual neurological health.

“For those with existing neurological conditions who may be concerned, it would be sensible to ask your specialist for information and advice. You may be able to help in this regard by documenting your own individual experience during adverse weather events, for example, to help devise strategies to try to prevent some of the consequences. It is also important to follow NHS advice about keeping safe and well during adverse weather events, such as heatwaves, cold snaps and flooding.”

Image credit: Pexels

Biography

Professor Sanjay Sisodiya is professor of neurology at UCL Institute of Neurology and honorary consultant neurologist at the National Hospital for Neurology and Neurosurgery and the Epilepsy Society.

Professor Sisodiya studied medicine at the University of Cambridge and Guy’s Hospital, and trained in Neurology in Oxford and at the National Hospital for Neurology and Neurosurgery.

He was awarded a PhD for working in brain magnetic resonance imaging in epilepsy. His key interests are in epilepsy, difficult-to-treat epilepsy, epilepsy genetics and treatment-response genetics and translational neurology, which are also his key research interests. He runs epilepsy and specialist epilepsy genomics clinics. He is the chief investigator of several international projects.