Tim Tai, Senior Photographer

The CDC reports the risk of suffering a stroke increases as we age, and it mainly occurs in older patients. However, climate change might bring that risk to young adults as well. 

A study released last month by the School of Public Health and School of Medicine revealed just how much havoc climate change can wreak on the bodies of young adults. In the study, researchers found that short-term exposure to high temperatures could substantially increase the risk of stroke for adults aged between 18-64, especially for women. 

“We have seen that over the past decades, the stroke instances in younger adults have been increasing in the United States,” Kai Chen, co-director of the Yale Center on Climate Change and Health and co-author of the study, told the News. “So we decided to determine whether temperature could be a risk factor correlated with higher stroke instances among young adults. And it does.”

Context and inspiration

Stroke is a condition where a blood clot in the brain blocks blood supply to the organ. It is usually correlated with being overweight or obese, chronic hypertension hypertension, smoking and diabetes. 

According to Dr. Adam de Havenon, associate professor of neurology at the School of Medicine, stroke risk factors are becoming more prevalent in younger age groups, because fewer young people have access to healthy food or have time to be physically active. Conditions like Type II diabetes, which is caused by a dysregulated metabolic process, are starting to appear in people in their 30s and 40s.

The climate change crisis has led to higher temperatures all over the country where there’s been a 2.5 degrees Fahrenheit increase in temperatures. According to Chen, this has had various devastating results, including the deaths of more than 30 people a year from the extreme heat in Connecticut. And in places like Phoenix and Houston, where temperatures regularly reach triple digits in the summer, effects could even be more devastating.

“Climate change is associated with risks for infectious diseases like tick-borne diseases, Lyme disease, mosquito-borne diseases,” Daniel Carrion, associate professor of epidemiology at the School of Public Health, told the News. “There are also many health outcomes associated with extreme temperatures, including cardiovascular, renal, respiratory diseases, psychiatric outcomes and there’s even some evidence that extreme temperatures can increase the risk of overdose deaths.”

According to Chen, there have been many studies that have found associations between air pollution — an environmental risk factor — and higher incidences of stroke. But it’s only been recently determined that high temperatures are also correlated with an increased presence of stroke. 

“In terms of biological mechanism, the extreme heat could lead to what we call hyper vicious blood,” Chen said. “When we are exposed to high temperatures, we sweat a lot and get dehydrated. This makes your blood and heart work harder to cope with the heat stress. This can then increase the risk of blood clots, which leads to an increase of stroke risks.”

Recent studies have shown that extreme temperatures, including extreme cold, can lead to a higher risk of stroke for adults above the age of 65. However, with the advent of more young people experiencing a stroke, the researchers wanted to focus on the overlooked population of adults aged between 18-64. 

According to Chen, determining this correlation for young adults will allow them to not overlook the danger that high temperatures present to their bodies as well. 

Additionally, young adults are more prone to be outside due to work, entertainment, and other purposes, placing them at a unique risk for the damaging effects of high temperatures, including stroke.

Disparities in the results

According to Chen, the researchers found that there is an increased risk for young adults having a stroke if you are exposed to higher ambient temperature or the outside air temperature. They also found that women had a higher risk of experiencing stroke due to high temperatures than their male counterparts. He reasons, though not confirmed, that this is due to their different physiological conditions, such as pregnancy and hormonal changes. 

Additionally, though not as statistically significant, they found that non-Hispanic Black individuals and neighborhoods of low socioeconomic status are more likely to experience a high stroke risk due to increased temperatures. 

According to Carrion, this can be due to various reasons. One reason is the presence of urban heat islands in cities like New Haven, where people of color experience more heat exposure and higher overall temperatures than other neighborhoods in the area; this is because they have lower access to adaptation strategies like regular air conditioning. 

“Another reason is residential segregation,” Carrion said. “Neighborhoods that are segregated with more black and brown folks tend to have less green space, have more concrete and asphalt and tend to be more urbanized surfaces. This leads to higher systemic exposures to these temperatures.”

Avenues of application

According to Carrion, various interventions are already in place to reduce the impact of extreme temperatures. The National Oceanic and Atmospheric Administration, or NOAA, will put out alerts on phones whenever there are extreme temperatures for a particular day that recommend drinking water and staying indoors. There are cooling centers where people can go if they don’t have access to AC.

Other interventions that Carrion believes could be geared to young people most at risk for exposure to extreme temperatures include the Low Income Home Energy Assistance Program; some states are using the program to support people to help keep themselves cool during the extreme heat of the summer. Another possible avenue is using Medicaid dollars to pay for getting AC in the home; this provides a better incentive to stay at home during times of extreme heat. 

Temperatures throughout the year aren’t usually at an extreme number. However, even relatively moderate exposure to heat has been shown to increase the risk of stroke among young adults. 

“We should not only focus on these extreme heat days,” Chen warned. “So, for example, let’s say we have a heat wave for only three days in the summer. We should not only focus on those three days, because there are many other very hot days and we still have an increased risk. I think we should make it clear to the public so that they know that if there’s no heat warning, that doesn’t mean you will have no risk.”

Chen also makes it clear that there needs to be a societal approach to reducing the risk of stroke. Some people won’t be able to go to cooling centers for cultural reasons or traffic access. The individual responsibility of keeping oneself from the dangers of extreme heat is valid; however, the government needs to take the lead in reducing the environmental risks of stroke in a community that creates disparities in health.

However, according to de Havenon, he doesn’t believe that high, extreme temperatures don’t have that much of an impact on young adults’ stroke risk as compared to other risk factors like hypertension and diabetes. He believes that even small improvements in smoking, physical inactivity and addressing obesity outweigh the benefit of the individual and society addressing the temperature-related risk of stroke. 

“We can all agree that, like, we shouldn’t expose people to dangerous levels of heat, and certainly that is happening in the United States, and this can lead to higher risks for stroke,” de Havenon said. “But I would argue that extreme heat provides a higher risk of cardiovascular mortality more than stroke, in my opinion. So for stroke risk, I would rather focus on getting patients to control their blood pressure.”

According to the National Institutes of Health, 10 to 15 percent of strokes that occurred in the United States during 2021 were among adults aged between 18 and 50.