Nimble Nonagenarians: Slower Biological Aging Increases Likelihood of Being a Healthy 90-Year-Old
Women make up a significantly larger portion of long-lived people, outnumbering men three-to-one in the 90-plus crowd. This ratio is why a multi-institutional team of researchers led by the Herbert Wertheim School of Public Health and Human Longevity Science at the University of California San Diego (UCSD) chose to study biological aging—the internal deterioration of our cells, tissues, and organs—in a cohort of nonagenarian women. In this study published in JAMA Network Open, Jain and colleagues show that slower biological aging is associated with both longer lifespan and healthspan, as seen by women who lived to age 90 without physical or cognitive impairments—turning the term nonagenarian into “non-agerians”.
(Chronological) Age Is Just a Number
Researchers now know that our chronological age—how many birthdays we’ve had—is not always the best measure of health and longevity. As the principal investigator of this study, Andrea LaCroix, Ph.D., M.P.H of UCSD, states, “Older people know well that age is just a number that may not be indicative of their health status. What if we had a way to measure how fast we were aging that could predict our odds of living a long and healthy life? In aging research, we call this an individual’s healthspan.”
One leading method of assessing the biological aging that affects healthspan is looking at changes to our DNA, known as methylation. Methylation is the addition or removal of chemicals called methyl groups to strands of DNA, which doesn’t change the DNA sequence itself but, instead, leads to alterations in gene activity.
DNA methylation is a significant component of epigenetics—the study of how gene activity changes in response to the environment, including diet, lifestyle, toxin exposure, stress, or UV radiation. These chemical changes to DNA often occur long before symptoms of diseases appear, making epigenetics a valuable way to predict age-related bodily decline. As unhealthy aging tends to increase the amount of methylated DNA, this tool known as an epigenetic clock is often considered an excellent representation of biological age.
Accelerated Epigenetic Aging Leads to Declining Healthspan
Jain and colleagues compiled data from three cohorts of over 1,800 older women who were followed for an average of 20 years, classifying them as surviving to age 90 with or without intact mobility and cognition or passing away before reaching 90. Physical mobility was assessed by the ability to walk around one block or climb one flight of stairs, while cognitive function was measured by annual surveillance of self-reported or physician-diagnosed memory problems.
They also used DNA methylation data from four epigenetic clocks to track epigenetic age acceleration, which indicated women who were aging faster biologically compared to their chronological age. Slower epigenetic aging would mean that someone’s chronological age was higher than their biological age—for example, a 90-year-old woman whose internal age was 70 or 80.
This epigenetic data found that each 5-8-year increase in epigenetic age acceleration was linked to a 20-32% reduced odds of living to age 90 with intact mobility and cognition. The results indicate that someone who was 80 years old chronologically but biologically was 88 would have almost one-third less of a chance of making it to age 90 with healthy memory and physical function.
The long-lived women in these cohorts tended to share some other characteristics, including being white, not having chronic health conditions at the start of the study (about age 70), graduating college, not smoking, and walking multiple times per week.
As the first author of this study, Purva Jain, Ph.D. of UCSD, states of these findings, “Prior studies have shown that epigenetic age acceleration is associated with increased risk of death, and a few studies observed that slower age acceleration occurs among long-lived individuals. But this is the first study to prospectively examine the relationship between slower age acceleration and living to age 90 with preserved mobility and memory.”
Using Epigenetic Clocks To Predict Future Health
These results suggest that measuring epigenetic age acceleration may be a useful and valid biomarker for assessing healthy longevity—both lifespan and healthspan—in older women. Most people would consider the goal of aging not simply to reach the age of 100 but to achieve these older ages while also retaining mobility, physical function, and memory. With this study, the UCSD researchers indicate that epigenetic clocks could be used to predict how healthy your life as a golden ager might be—and to give you time to turn things around if your biological age isn’t where you want it to be.
Dr. Jain concludes, “Furthermore, our study suggests we can use epigenetic age acceleration to estimate the risk of an individual not attaining healthy longevity, which could lead to future public health interventions to counteract poor health outcomes among older populations.”
Jain P, Binder AM, Chen B, et al. Analysis of Epigenetic Age Acceleration and Healthy Longevity Among Older US Women. JAMA Netw Open. 2022;5(7):e2223285. doi:10.1001/jamanetworkopen.2022.23285