Scientists have discovered that people age dramatically in two periods: at age 44, and then at age 60.
If you’ve noticed a sudden buildup of wrinkles, aches and pains, or a general feeling of aging overnight, there may be a scientific explanation. Research suggests that aging isn’t a slow, steady process, but occurs in at least two accelerated bursts.
The study, which tracked thousands of different molecules in people aged 25 to 75, found two major waves of age-related changes around age 44 and again around age 60. The findings could explain why spikes in certain health problems, including musculoskeletal problems and cardiovascular disease, occur at certain ages.
“We’re not just changing gradually over time. There are really dramatic changes,” said Prof Michael Snyder, geneticist and director of the Center for Genomics and Personalized Medicine at Stanford University and lead author of the study.
“It turns out that the mid-1940s is a time of dramatic change, just like the early 1960s – and that’s true no matter what class of molecules you’re looking at.”
The study followed 108 volunteers, who provided blood and stool samples and skin, mouth and nose swabs every few months for anywhere from one to nearly seven years. Researchers assessed 135,000 different molecules (RNA, proteins and metabolites) and microbes (the bacteria, viruses and fungi that live in the participants’ guts and on their skin).
The abundance of most molecules and microbes did not shift in a gradual, chronological manner. When scientists looked for clusters of molecules with the largest shifts, they found that these transformations tended to occur when people were in their mid-40s and early 60s.
The peak in aging in the mid-40s was unexpected and initially thought to be the result of perimenopausal changes in women, which skewed the results for the group as a whole. But the data revealed that similar shifts were also occurring in men in their mid-40s.
“This suggests that while menopause or perimenopause may contribute to the changes seen in women in their 40s, there are likely other, more important factors influencing these changes in both men and women,” said Dr Xiaotao Shen, a former postdoctoral researcher at Stanford School of Medicine and first author of the study who is now at Nanyang Technological University Singapore.
The first wave of changes included molecules related to cardiovascular disease and the ability to metabolize caffeine, alcohol, and lipids. The second wave of changes included molecules involved in immune regulation, carbohydrate metabolism, and kidney function. Molecules related to skin and muscle aging changed at both time points. Previous research suggested that a later peak in aging can occur around the age of 78, but the latest study could not confirm this because the oldest participants were 75 years old.
The pattern fits with previous evidence that the risk of many age-related diseases does not increase gradually, with the risk of Alzheimer’s and cardiovascular disease rising sharply after age 60. It is also possible that some of the changes are related to lifestyle or behavioral factors. For example, the change in alcohol metabolism may be due to an increase in consumption in people in their mid-40s, which can be a stressful time in life.
The findings could help target interventions, such as increasing exercise during periods of more rapid muscle loss, the authors said. “I’m a big believer in the idea that we should make lifestyle changes while we’re still healthy,” Snyder said.
The findings are published in the journal Natural aging.