Heat waves can lead to cognitive decline

Heat peaks and heat waves are increasing in France, but not only. In the United States too, the heat affects the health of the most vulnerable. According to a study by scientists from New York University, older African-Americans and those living in poor neighborhoods would be the most affected by these climate changes, with a greater impact on their mental health.

Can the heat make us lose our minds?

Recent studies have already shown the impact of exposure to a heat wave, on an ad hoc basis. But as part of this study, the scientists wanted to demonstrate the long-term consequences of this exposure on the cognitive abilities of the participants.

For this work, the researchers therefore analyzed data from nearly 9,500 American adults aged 52 and over interviewed over a 12-year period, between 2006 and 2018, as part of a study led by the Research Institute. social from the University of Michigan.

The experts also looked at the socioeconomic conditions of the neighborhoods where the participants lived. And they finally calculated the cumulative exposure to extreme heat of the participants, or the number of days during which temperatures reached or exceeded a specific threshold during this 12-year follow-up.

Cognitive health affected by these heat waves

Result: they found that high exposure to extreme heat was associated with faster cognitive decline in residents of poor neighborhoods, but not for those in wealthy neighborhoods. Additionally, cumulative exposure to extreme heat was associated with faster cognitive decline in black seniors, but not in white or Hispanic seniors.

“Our research reveals that cumulative exposure to extreme heat can harm cognitive health, but it does so unevenly across the population.said Eunyoung Choi, first author of the study.

“Cognitive decline may not manifest immediately after a single thermal event, but repeated or prolonged exposures to extreme heat may be detrimental” adds Virginie Chang, associate professor of social and behavioral sciences at the NYU School of Global Public Health and lead author of the study.

“Cumulative exposure to extreme heat can trigger a cascade of events in the brain, including cell damage, inflammation, and oxidative stress, all of which can deplete its cognitive reserve.“.

Poor neighborhoods most affected

How can we explain the difference in the impact of these heat waves according to socio-economic level? The answer is quite simple:Affluent neighborhoods tend to have resources that can help during a heat wave: things like well-maintained green spaces or air conditioning. In disadvantaged neighborhoods, these resources may not exist” explains Haena Lee, assistant professor of sociology at Sungkyunkwan University, South Korea and co-first author of the study.

“Other factors associated with poor neighborhoods, such as chronic stress, greater social isolation, and less access to specialized cognitive health services for these residents, may also contribute to this disparity.” she concludes.

Slide: Heat wave, high heat… What are the risks for our body?