A landmark study has found that humans age in two major bursts and do not proceed continuously with age, at a slow pace. According to research published by Nature Aging, these growth spurts occur at ages 44 and 60. Maybe these are why people have an alarming rate of health problems associated with aging during such periods.
The Stanford University study tracked over 135,000 types of molecules and microbes in 108 participants aged 25 through 75 for a multi-year period. Blood, stool, skin, nasal, and oral samples were collected every few months to detect dramatic shifts in molecular and microbial abundance.
“We’re not just slowly evolving. There are some really dramatic changes,” said Prof. Michael Snyder, a geneticist and director of the Center for Genomics and Personalized Medicine at Stanford University, who is also the senior author of the study. He said these changes were evident across many classes of molecules, among those that are connected to cardiovascular disease and metabolism.
The first wave of changes, occurring in the mid-40s, involves molecules associated with cardiovascular health and how the body metabolizes caffeine, alcohol, and lipids. The second, occurring around age 60 includes molecules related to immune regulation, carbohydrate metabolism, and kidney function. On both occasions, there are changes in skin and muscle aging.
Scientists first suspected the mid-40s spike might be driven by perimenopausal changes in women. But similar shifts were seen in men. That implicated other major factors. Dr. Xiaotao Shen, a former postdoctoral scholar at Stanford, now at Nanyang Technological University Singapore, said, “Although menopause might play a role in these changes for women, some other factor is driving it in both genders.”.
Results agreed with prior evidence that the risk of many diseases, including Alzheimer’s and cardiovascular disease, climbs precipitously after 60. This may be due to molecular changes fostered by lifestyle and behavioral factors, such as increased consumption of alcohol during stressful mid-40s.
Understanding these bursts of aging could lead to targeted interventions. “I’m a big believer that we should try to adjust our lifestyles while we’re still healthy,” Snyder said, suggesting that increased exercise during periods of rapid muscle loss could be beneficial.
Though the new study brings fresh insights into the aging process, experts say more work should be done to understand what these findings might portend. “The detailed molecular changes pinpointed in this study are a bit like first looking through a microscope,” said Dr. Josef Coresh of NYU Grossman School of Medicine. “It gives you the level of detail, but it does not tell you how important they will be for long-term health.”.
The findings could eventually lead to more personalized approaches to aging, with major gains in health and quality of life during the critical periods of life.