New research is giving further insight into how humans age — and it’s not the gradual process many of us believe it is. A study published in the journal Nature Aging indicates that most significant age-related changes occur in two major phases: at approximately age 44 and again at age 60.
“We’re not just changing gradually over time. There are some really dramatic changes,” Professor Michael Snyder, a geneticist and director of the Center for Genomics and Personalized Medicine at Stanford University and senior author of the study, told The Guardian.
The findings were gleaned by monitoring 135,000 various molecules and microbes in 108 healthy individuals of diverse ethnic backgrounds between the ages of 25 and 75. Tracking their molecular changes from a median of 1.7 years to a maximum of 6.8 years, participants submitted samples of their blood and stool as well as skin, oral, and nasal swabs every three to six months. Surprisingly, researchers found that rather than shifting in a predictable, progressive manner, the most significant molecular changes occurred in subjects in their mid-40s and early 60s.
“It turns out the mid-40s is a time of dramatic change, as is the early 60s – and that’s true no matter what class of molecules you look at,” said Prof. Snyder of the research.
Furthermore, despite presumptions that perimenopausal and menopausal symptoms often experienced by women in their mid-40s might skew the results, significant shifts occurred equally across genders.
“This suggests that while menopause or perimenopause may contribute to the changes observed in women in their mid-40s, there are likely other, more significant factors influencing these changes in both men and women,” said the first author of the study, Dr. Xiaotao Shen of Nanyang Technological University Singapore, a former postdoctoral scholar at Stanford.
While visible shifts in skin and muscle aging occur in both the mid-40s and early 60s, internal changes initially occur in molecules that regulate the metabolization of caffeine and alcohol, as well as some linked to cardiovascular disease. Second-phase shifts affect molecules that regulate immunity, kidney function and carbohydrate metabolism. Prior research indicated a third phase of major age-related changes might occur around 78, but as the threshold for the oldest participants in the latest research was 75, this is, as yet, unconfirmed.
In addition to further explaining why the risk of developing diseases like Alzheimer’s, cardiovascular events and general mortality risk dramatically spikes after age 60, researchers are optimistic their findings can be useful in preventative care.
“I’m a big believer that we should try to adjust our lifestyles while we’re still healthy,” said Prof. Snyder.
At the very least, if you are a person of a certain age who feels like you’ve aged significantly almost overnight, rest assured: It’s not your imagination.