- The brain is especially vulnerable to heat because it cannot cool itself, making high temperatures risky for people with neurological conditions like epilepsy.
- The global climate crisis is making weather more dangerous, and it’s going to get worse.
- Hot weather can trigger more frequent and severe seizures. Scientists are researching exactly how heat impacts brain function and seizure activity so they can find solutions.
At an average temperature of 100.4 degrees Fahrenheit, the brain is the hottest part of the human body. Its cellular machinery has no way of cooling itself down. In the heat of brutal summers that are only growing worse with climate change, your brain is compromised.
As the mother of a teen with epilepsy, Emma Campbell knows this problem well. Her daughter, Arwen, experiences more severe and frequent seizures in the heat, Campbell explains in a video. Arwen is unable to join her classmates on class trips in hot weather. As soon as summer is on the horizon, the Campbells need to keep all of their curtains, blinds and windows shut. “We need her to live as normal a life as possible,” Campbell says. “But it would be nice if more people were aware of the impacts of heat, not just on epilepsy, but a lot of different medical conditions.”
The human-generated climate crisis sweeping our planet means Earth is becoming a less hospitable place for people with epilepsy and other health conditions aggravated by heat, including heart disease, diabetes, and dementia. Researchers have discovered that, among its more insidious effects, the repercussions of climate change have reached the human brain. This affects the roughly 50 million people worldwide who live with epilepsy.
FutureNeuro Research Ireland Centre for Translational Brain Science has observed a disturbing trend in brain cells that are particularly sensitive to temperature. Temperatures that continue to rise are proving to make neurological conditions such as epilepsy, schizophrenia, Alzheimer’s and Parkinson’s worse. In the case of epilepsy, scorching conditions could lead to more severe and frequent seizures.
A special commission of the International League Against Epilepsy (ILAE) is now studying the problem. The ILAE is a global organization through which clinicians and scientists join forces to gauge the impact of climate change on brain function.
A major priority of the commission is to ask what FutureNeuro’s director and ILAE chairman, David Henshall, Ph.D., calls “the big research questions” regarding epilepsy—do we understand enough about the detrimental events of rising temperatures on brain function and mental health? “What kind of brain imaging work can we do, what can we understand about how brain cells function, and what is the breaking point in the brain if we do experience extreme sustained temperatures?” says Henshall, who is also professor of physiology and medical physics at the Royal College of Surgeons in Ireland.
His research shows that in some genetic types of epilepsy, the gene behind the condition sends messages to brain cells to build a protein that is especially sensitive to temperature. Heat is a catalyst that speeds up chemical reactions in cells, and seizures caused by enzyme reactions which are already compromised could worsen if temperatures keep crawling higher.
“From recording brain cell activity, we know that as you get above this temperature, brain cells start to behave differently and just fire synchronously, which is what happens during a seizure,” said Henshall. “It is very disruptive to brain function when they all fire together. Unfortunately, there is a gap in quality clinical data on how widespread and extensive this problem is.”
The brain is like a laptop that can overheat easily and malfunction, or even shut down, but has no built-in fan to cool itself off. Whether or not someone is accustomed to a hot climate and is more resilient to slight temperature changes may influence seizure frequency and severity. How exactly excess heat affects the hypothalamus, the part of the brain that regulates bodily responses to shifts in temperature, is another factor. The hypothalamic-pituitary-adrenal axis, an important system involved in the body’s stress response, is the part of the hypothalamus especially prone to seizures.
Relentless heat in many parts of the world, especially tropical and subtropical regions, has scientists delving into how much the climate factors into the onset and severity of epileptic seizures. They are also concerned about possible seizure triggers, such as the spread of infectious diseases like malaria in hot and humid climates.
“It is not just temperature peaks that are relevant, but unseasonal temperatures, too,” says neurologist Dr. Sanjay Sisodiya, Ph.D., a prominent member of the ILAE who focuses on how heat affects epilepsy. “How exactly such temperatures act to influence thermoregulation and brain function in people with neurological disorders is not yet well understood, but if brain structure and function is already compromised, one can imagine that functions such as thermoregulation might be further compromised.”
Sisodiya led an investigative study with colleagues, including theoretical neuroscientist Dr. Karl Friston, Ph.D., whose work involves the intersection of brain function and physics. They fear that the worst heat-generated problem with epilepsy will be more frequent or severe seizures. Some forms of epilepsy, such as Dravet syndrome, are caused by a gene mutation, and researchers have shown that unrelenting heat can exacerbate seizures and other symptoms of this condition.
With humidity only aggravating the effects of heat, people in tropical climates will feel the brunt of global warming, with the most vulnerable living in poorer areas where access to electricity is often limited. This could have disastrous consequences for both symptoms and treatments of neurological conditions. Henshall recalls speaking with doctors and patients in rural parts of India and Southeast Asia, where the struggle for electricity often means no air conditioning or refrigeration. He was distressed when shown a video clip of an epilepsy medication that had melted.
“The largest proportion of people with epilepsy are in these countries,” he said. That’s because there are higher incidences of infection disease and birth trauma there, both of which can cause epilepsy.
Alongside finding ways to counteract climate change, Sisodiya thinks that more research is urgently needed to understand and treat symptoms of epilepsy and other conditions that have been magnified in the warming environment. He is optimistic but determined.
“We need to understand what the risks are, who is most vulnerable and why, what the mechanisms underlying the risks are, and then act on that information,” he said. “We may not be able to prevent all the adverse effects on the brain, but if we can define those risks and effects, there will be things we can do.”
Elizabeth Rayne is a creature who writes. Her work has appeared in Popular Mechanics, Ars Technica, SYFY WIRE, Space.com, Live Science, Den of Geek, Forbidden Futures and Collective Tales. She lurks right outside New York City with her parrot, Lestat. When not writing, she can be found drawing, playing the piano or shapeshifting.