by It was a big shock when Michael Mosley, a well-known UK doctor and TV presenter, was found dead earlier this month after being exposed to scorching temperatures on the Greek island of Symi.
But it is now one of a series of deaths and tourist disappearances in Greece as the country endures a powerful heat wave in early summer with temperatures pushing above 40 degrees Celsius (104 degrees Fahrenheit).
On Saturday, a Dutch tourist was found dead on the island of Samos. The next day, the body of an American tourist was found on Mathraki, a small island west of Corfu. Albert Calibet, another American tourist, has been missing since he went out for a hike on June 11 on Amorgos. And two French women disappeared on Sikinos after they went for a walk.
The bodies of those who died have yet to be examined to determine the exact cause of death, but authorities are warning people not to underestimate the impact of searing temperatures.
“There is a common pattern,” Petros Vassilakis, the police spokesman for the South Aegean, told Reuters, “they all went for a walk amid high temperatures.”
Some scientists say that what is happening in Greece gives a warning sign about the effects of extreme heat on the body, and in particular the brain, which can cause confusion, affecting people’s decision-making ability and even their -perception of risk.
As climate change brings longer and more intense heat waves, scientists are trying to figure out how our brains will cope.
The brain is ‘the master switch’
Research has traditionally focused on the effects of extreme heat on muscles, skin, lungs and heart, but “I think the key to everything is the brain,” said Damian Bailey, professor of physiology and biochemistry in University of Ireland. South Wales. It’s the “master switch” for the body, he told CNN.
Body temperature is regulated in the brain. The hypothalamus, a small diamond-shaped structure, acts as a thermostat. It performs a delicate dance to maintain the body’s internal temperature at or very close to 37 degrees Celsius (98.6 Fahrenheit). When it is hot, the hypothalamus activates the sweat glands and dilates blood vessels to cool the body.
But the brain functions well within a narrow range of temperatures and can be affected by even small changes. Many people will be familiar with feeling sluggish and lazy on a hot summer day.
But as heat increases, it can have serious effects, including lowering body fluids and reducing blood flow to the brain, Bailey said. It compares the brain to a Hummer – it requires huge resources to function.
Tests he ran on research participants in an environmental chamber, where he raised the temperature from 21 to 40 degrees Celsius (about 70 to 104 degrees Fahrenheit), showed a reduction in blood flow to the brain of about 9% to 10% .
“That’s a big thing when it comes to not getting enough fuel into an engine that’s running high all the time,” Bailey said.
And it has an impact. Extreme heat can disrupt normal brain activity, said Kim Meidenbauer, a neuroscientist at Washington State University. Brain networks that allow people to think clearly, reason, remember, and construct and formulate ideas can be “thrown out of whack,” she told CNN.
It becomes more difficult to make complex decisions, such as which way to go for a walk — a decision that is simple but requires weighing many different factors.
There is also evidence to suggest that people are more likely to make risky decisions and engage in impulsive behavior when exposed to heat, she said.
Altered risk perception combined with impaired cognitive function can have very serious consequences. “You’re not just talking about maybe getting a little too hot and maybe getting a sunburn,” she said. “You’re talking about potentially life-threatening (situations), like making poor decisions, clouding your judgment.”
Scientists are only beginning to unravel the range of effects that heat has on the brain, not just in terms of decision-making but in terms of mood, emotions and mental health.
“We really have little understanding,” Meidenbauer said. “It’s a big unknown at this point.”
Who is vulnerable?
Some people are more sensitive to heat than others. The elderly, especially those over 65, are at greater risk, as their bodies do not always thermoregulate as well. The people who went missing in Greece were in their mid-50s and older.
Very young children and pregnant women also face an increased risk, as do those with pre-existing conditions, including mental health conditions.
But heat can be dangerous for anyone.
In 2016, a team of scientists followed 44 college students during a heat wave in Boston and found that there was a significant decline in cognitive performance among those without air conditioning.
“No one is immune to the health effects of heat,” said Jose Guillermo Cedeño Laurent, one of the study’s authors and an assistant professor at the Rutgers School of Public Health. “Our brain is a very sensitive organ,” he said.
Someone who is very fit and carries plenty of water is still gambling if they decide to go hiking in extreme temperatures, Bailey said.
“You make wrong decisions and it can cost you your life.”
How to protect yourself
There are behavioral things people can do to protect themselves and reduce risk, experts say.
These include not exercising during the hottest parts of the day, instead going to the cooler parts of the day and seeking shade when possible. Wearing loose clothing and applying ice packs to the head and neck can also help.
Drinking water is key and not just when you feel very thirsty, Bailey said. It is important not to reach the point where the body is losing fluids faster than it can take them in. Experts also recommend electrolyte drinks, which can help replace some of the fluids lost through sweating.
Use location-sharing apps, Meidenbauer said. “Make sure someone knows where you are.”
Over the long term, regular exercise is important – provided it’s not outside during the hottest parts of the day – as it can help the body to thermocouple. “The more fit you are to these climatic stressors,” Bailey said.
It will take time to find the exact reasons for the deaths of those who lost their lives in Greece but there is a lesson that can still be learned from the tragedies, said Bailey.
“It doesn’t matter how smart or how fit you are … if you’re going out in 40 degree celsius plus temperatures, even if you’re well prepared, you’re running the gauntlet.”
CNN’s Stephanie Halasz and Issy Ronald contributed to this report.
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