How Heat Speeds Up Ageing
Ageing naturally occurs at different rates among individuals, influenced by various stresses. Sustained heat is now emerging as a critical factor that accelerates this process by inducing epigenetic changes—altering how our genes are expressed without changing our underlying DNA.The study specifically focused on DNA methylation (DNAm), a well-documented epigenetic process. DNAm involves adding chemical markers that activate or silence genes, influencing protein production and physiological functions. Severe heat stress, the study found, can cause lasting changes in these gene expression patterns, resulting in faster biological ageing.
Major Findings of the USC Study
The study, involving participants averaging 68 years old, assessed the impact of intense heat experienced over six years (2010–2016). Researchers employed three different biological clocks—PcPhenoAge, PCGrimAge, and DunedinPACE—to accurately measure ageing rates through epigenetic markers found in blood samples.Key highlights of the findings include:
- Significant Age Acceleration: According to the PcPhenoAge measure, prolonged heat exposure increased biological ageing by up to 2.48 years more than typical ageing.
- Variation Between Biological Clocks: The PCGrimAge clock showed an ageing increase of 1.09 years, whereas DunedinPACE indicated a smaller impact of 0.05 years.
Implications for Public Health in a Warming Climate
With global temperatures rising, these findings have profound implications, especially for heat-prone countries like Australia. Extreme heat not only contributes to immediate health risks such as heatstroke but also subtly deteriorates health over time by speeding up biological ageing, potentially leading to earlier onset of age-related diseases and disabilities.Older individuals are particularly vulnerable because their ability to regulate body temperature decreases with age, making them less resilient to environmental stresses.
Research Gaps and Future Directions
Despite robust findings, researchers acknowledge several limitations, such as the lack of information regarding participants' use of air conditioning or their outdoor activities, factors that might influence individual exposure to heat.This new study represents a significant advancement in human epigenetic research, which previously focused primarily on animals and plants. Prior to this, only a handful of limited human studies had explored how environmental heat affects epigenetics.
As climate change intensifies, further research is urgently needed to understand if and how human populations can adapt to these epigenetic changes.
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