Epigenetic Testing May Predict Aging, Mortality

Epigenetic changes, measured by DNA methylation, may be a predictor of biological age, according to a study published in the September issue of Aging. The multicenter study found that epigenetic age predicts all-cause mortality above and beyond chronological age and traditional risk factors.

The meta-analysis included 13 different cohorts, including large studies like the Framingham Heart Study and the Women’s Health Initiative, for a total sample size of 13,089 individuals, (non-Hispanic whites, n=9,215; Hispanics, n=431; and Blacks n=3,443). Epigenetic age was measured using two methods—relying upon markers assessing methylation of cytosine linked to guanine by a phosphate group (CpGs). Additionally, the researchers examined whether incorporating information on blood cell composition, which changes during aging, into the epigenetic age metrics improves predictive power for identifying mortality risk. Chronological age was compared to the blood’s biological age, creating an epigenetic clock (AgeAccel) to predict each person’s life expectancy. A positive value of AgeAccel indicated that the epigenetic age was higher than expected, based on chronological age.

The researchers found that measures of epigenetic age acceleration were significantly predictive of mortality, independent of chronological age and traditional risk factors (e.g., smoking status, physical activity status, or major chronic diseases), across all racial and ethnic groups. Incorporation of blood cell composition into epigenetic age measures resulted in even more accurate estimations of time to death.

“While epigenetic processes are unlikely to be the only mediators of chronological age on mortality—in fact, multiple risk factors have stronger effects on mortality—our results suggest that at least one of the mediating processes relates to the epigenetic age of blood tissue and that this process is independent of age-dependent changes in blood cell composition,” write the authors led by Brian Chen, a fellow from the National Institute of Aging on Baltimore, Md.

About five percent of the participants aged at a faster biological rate, which is associated with approximately a 50 percent increased risk of death and a shorter life expectancy. In contrast, 20 percent of participants age at a slower biological rate, which was tied to a decreased risk of death.

Principal investigator Steve Horvath, Ph.D., Sc.D., from University of California, Los Angeles, explains that if two 60-year-old men both smoked to deal with high stress, but one of the man’s epigenetic aging rate ranks in the top 5 percent, while the second’s aging rate is average, the likelihood of the first man dying within the next 10 years is 75 percent compared to 60 percent for the second.

Takeaway: Epigenetic changes, measured by DNA methylation and blood cell composition, may predict biological age and related mortality risk.