🌡️ Heat waves may age us as much as tobacco or alcohol

Extreme heat doesn't just test our bodies on a daily basis. It could also influence the speed at which our cells age. Researchers are increasingly interested in this subtle but profound link between heat waves and premature bodily wear and tear.

Known for disrupting sleep or worsening chronic diseases, heat waves are now revealing a more insidious impact: the acceleration of biological aging. Published in Nature Climate Change, a large study conducted in Taiwan sheds light on this unexpected relationship. It suggests that climate change, by multiplying heat waves, could also transform our relationship with the passage of time within our bodies.

Aging measured in thousands of people

Nearly 25,000 residents of Taiwan were followed for about fifteen years. Their biological age was estimated using a series of health indicators, ranging from blood pressure to liver parameters. The researchers then cross-referenced this data with the participants' exposure to heat waves. The results showed a growing gap between chronological age and biological age in the hottest areas. For the most exposed quarter, aging accelerated by about 3% per year. Manual laborers and rural residents, often without air conditioning, were among the most affected.

This finding is not limited to Asia. In the United States, another study of more than 3,600 elderly people recently highlighted chemical alterations in DNA linked to heat. These changes constitute objective signs of accelerated aging.

The consequences are not just theoretical. They translate into an increased risk of heart attack, stroke, or diabetes—conditions that heavily impact life expectancy. Some researchers compare the overall impact of repeated exposure to that of smoking or excessive alcohol consumption.

The biological mechanisms of thermal wear

Several biological pathways are being explored to understand this influence of heat on aging. The reduction in the length of telomeres, those protective fragments at the ends of chromosomes, is among the main hypotheses.

Other researchers point to direct damage to DNA, which would alter the genetic stability of cells. Mitochondria, essential for energy production, would also be weakened by heat. These damages would lead to cellular senescence, a stage where the cell stops dividing and enters a phase of degradation. This process contributes to the overall aging of the organism.

Populations do not all react in the same way. Age, health status, and lifestyle also play a role. An elderly person already weakened by several heat waves could experience more pronounced aging than a young adult. Working outdoors or living without air conditioning further amplifies the observed effects.

Finally, researchers emphasize that air conditioners are not a sustainable solution. They provide individual comfort but release heat outside, worsening conditions for those who lack them. These elements remind us that heat-related accelerated aging is not uniform but depends on a combination of biological, social, and environmental factors.