Heat Waves Can Dull Even Young Minds, Study Says
As America sweats through another summer, new research suggests that heat waves can slow the brains of even healthy young adults.
In the face of extreme heat, college students living in dorms without air conditioning did worse on tests of mental skills than their cooled-off counterparts, researchers found.
Both test-taking speed and accuracy seemed to suffer, said study lead author Jose Cedeno Laurent.
"We are starting to experience the effects of climate change, and these include detrimental effects in the cognitive function of young and healthy individuals," said Cedeno Laurent, a research fellow at the Harvard School of Public Health.
Young people are usually considered resilient to heat exposures, but the study suggests they can experience negative effects in the way they learn, said Cedeno Laurent.
The findings also reveal a need to improve indoor temperature control, he added.
In many parts of the world, more frequent and severe heat waves will test the limits of existing infrastructure and "will demand adaptation measures to cope with unprecedented temperature levels," Cedeno Laurent said.
His team pointed out that 2016 was the warmest year on record for the past two centuries and that U.S. adults spend 90 percent of their time indoors.
"We see our study as a pioneering effort to find recipes for health, a set of recommendations on how to control our environments to cater to the needs of indoor living," Cedeno Laurent said.
The solution? Develop more energy-efficient buildings, he said.
For the study, Cedeno Laurent and his team followed 44 Boston students in their late teens and early 20s for 12 days in the summer of 2016. Twenty-four lived in dormitories with central air conditioning. The others lived in dorm rooms without air conditioning.
All the rooms had devices that measured temperature, carbon dioxide, humidity and noise levels. The researchers also tracked the students' physical activity and sleep patterns.
After five days of seasonable temperatures, the students endured a five-day heat wave followed by a two-day cool-down. They took two tests every morning on their smartphones.
In one test, they had to identify the color of word displays. This evaluated mental speed and focusing ability. The other test used basic arithmetic questions to assess cognitive speed and working memory.
Compared with students in air-conditioned rooms, those without cooling had 13 percent longer reaction times on color word tests. Their math scores were also 13 percent lower.
The study cannot prove a direct cause-and-effect relationship. Still, "our findings have profound implications to the way we see the impacts of climate change," said Cedeno Laurent.
The differences in mental ability were most significant when the outdoor temperature started to fall. That's likely because indoor temperatures remained high in the uncooled dorms.
When a heat wave breaks, the researchers said, people could be lulled into thinking the danger has passed, not realizing that many structures were built to retain heat.
The findings didn't surprise Dr. David Katz, director of the Yale-Griffin Prevention Research Center in Derby, Conn.
"Distraction is obviously bad for concentration, and discomfort is a distraction," said Katz, who is also past president of the American College of Lifestyle Medicine.
He agreed that the problem of climate change amplifies the importance and relevance of this study.
"As weather extremes become more frequent and widespread, so, too, does weather-related discomfort," Katz said.
Many problems have been linked to climate change, including rising seas, crop failures, emerging infections and depleted aquifers, he noted.
"We may now reasonably add a rising toll of climate-induced discomfort, distraction and cognitive impairment," Katz said.
The study was published online July 10 in the journal PLOS Medicine.
For more on climate change, visit NASA.
SOURCES: Jose Guillermo Cedeno Laurent, Sc.D., research fellow, Harvard T.H. Chan School of Public Health, Cambridge, Mass.; David Katz, M.D., M.P.H., director, Yale-Griffin Prevention Research Center, Derby, Conn., and past president, American College of Lifestyle Medicine; July 10, 2018, PLOS Medicine, online