Short-term heat exposure identified as a risk factor for stroke for younger adults

Short-term exposure to high environmental temperatures can significantly increase the risk of stroke in people ages 18 to 64, especially women, according to a new study from researchers at the Yale School of Public Health (YSPH) and Yale School of Medicine.

The study, which analyzed the health records of more than a million people across the country, highlights a growing concern about how climate change could worsen health outcomes in underserved populations.

“Climate change is one of the most important public health challenges of our time,” said Dr. Xiaomei Ma, Ph.D., professor and interim chair of YSPH’s Department of Chronic Disease Epidemiology. “It is critical to assess the health impacts of different aspects of climate change so that we can better adapt and potentially intervene.” Ma, co-senior author of the study, noted that 2024 is on track to be the hottest year on record.

The studypublication on October 23 in the Journal of the American College of Cardiologyspecifically aimed at adults aged 18 to 64, a demographic group that has seen an increasing burden of strokes in recent years, the authors said.

As global temperatures rise, the health consequences of extreme heat have become an urgent issue. Strokes, which are typically linked to factors such as high blood pressure and a sedentary lifestyle, can also be caused by environmental factors such as temperature, the authors said. Many previous studies of this link have focused on adults aged 65 and older, leaving a gap in understanding how heat exposure affects younger people, according to the authors.

The Yale study found that short-term exposure to high ambient temperatures (defined as the current day through the previous six days) may be a significant risk factor for stroke for younger adults, said Dr. Kai Chen, Ph.D., associate professor. of epidemiology (environmental health sciences) at YSPH and co-senior author of the study. In particular, Chen said the study found that women were more vulnerable to high environmental temperatures than men.

Explaining this finding, Chen explained: “The vulnerability in women is biologically plausible given the different physiological conditions and risk factors for stroke in women and men, such as pregnancy or hormonal changes around menopause. But more research is needed to better understand the contribution of these findings. both biological and socioeconomic factors in the sex differences we observed.”

The study used a large, nationwide health claims database, providing broad geographic coverage across the United States. By studying more than a million people aged 18 to 64, the researchers evaluated how short-term exposure to both high and low temperatures affected the risk of stroke. The study also included demographic data and used the Social Deprivation Index, a measure that quantifies the level of socio-economic deprivation in a given area, to take into account socio-demographic factors that could contribute to vulnerability to stroke .

The findings could have significant implications for public health policy, especially as climate change continues to pose new challenges, the authors said. Not only does the study identify temperature as a modifiable environmental risk factor for stroke, it also highlights the need for targeted interventions that protect at-risk populations, particularly younger adults and women.

The study also adds to the growing body of evidence that rising temperatures can worsen health inequalities, Chen said. Not only is the number of young adults experiencing stroke currently growing, but many people in this age range could also face a disproportionate burden of climate change due to the need to work outside the home or a lack of resources to cope with extreme temperatures. to cope, according to the authors. said.

Chen and Ma say the study highlights the value of interdisciplinary collaboration. They decided to start working on the current study after a chance meeting two years ago. Their diverse academic backgrounds allowed them to approach the issue of stroke risk from both environmental health and chronic disease perspectives.

“Kai and I first met two years ago, at a party in the beautiful backyard of a faculty member at the Yale School of the Environment,” Ma said. “We talked about what we were doing in our research, got inspired by each other and came to the conclusion that it would be great fun to work together. Sometimes people say that and they don’t necessarily follow through, but we both took action. “

Other authors of the study include Dr. Lingzhi Chu and Dr. Rong Wang from YSPH, and Dr. Cary Gross, from both the Yale School of Medicine and YSPH.