Scientists Link Epigenetic Age Acceleration to Mortality

By using four popular methylation clocks, scientists have established that epigenetic age acceleration (EAA) is linked to aging and mortality in human beings. The researchers analyzed data from the Women’s Health Initiative—an important population study with a sample size of 1813 women. Unfortunately, this was also one of the limitations of the study because on average, women live longer than men. 

That being said, the researchers analyzed the probability that the participants would survive to the age of 90, and whether or not they had impairments in cognition or mobility. They made an interesting observation that while surviving to the age of 90 was considered unique a few decades ago, it is now considered a suitable longevity threshold, especially in women. 

These samples were studied using four popular methylation clocks: GrimAge, PhenoAge, the Hannum clock, and the Horvath pan-tissue clock. 

From the 1813 individuals, 464 women survived to the age of 90 with intact mobility and cognitive function. On the other hand, 420 women survived to the age of 90 years without either intact mobility, cognitive functioning, or both. And lastly, 929 women did not survive.

The researchers also documented the profiles of the individuals, observing that women categorized as healthy at 90 having both cognitive function and mobility intact were likely to be white college graduates who had no history of smoking, had normal to slightly elevated BMI, and had a habit of walking at least 2 to 6 times a week. However, the final parameter was questionable; because while it makes sense to suggest that these women stayed healthy due to their regular walks, they might have also done these regular walks due to having good health in the first place. 

The study also demonstrates how important these aging clocks are. By determining the epigenetic age acceleration (EAA)—which is the difference between a person’s chronological age and biological age—we can establish whether or not someone is suffering from accelerated aging. 

In fact, the findings of the study demonstrate how all four epignentic clocks show a strong correlation between EAA and mortality. For every 1 standard deviation increase in EAA, the odds of surviving to the age of 90 with intact mobility and cognitive function compared to not surviving at all were lower by 20 and up to 40 percent depending on which clock was used. These numbers were also similar when only mobility was analyzed. 

The study, therefore, suggests that EAA might be a valid biomarker linked to longevity in elderly women. It also provides the first evidence that EAA correlates to human mortality, and is a vital step forward in documenting epigenetic clocks as reliable biomarkers of aging.