Study: Your body experiences 'massive' biomolecular changes in your 40s and 60s

Aging Americans, you're not imagining things: Big shifts in physical well-being do occur at certain points in the life span, new research shows.

A team at Stanford University has found "massive" changes during a person's mid-40s and early 60s in regard to the molecules and microorganisms that help maintain the body.

"We're not just changing gradually over time; there are some really dramatic changes," said study senior author Michael Snyder , chair of genetics at Stanford. "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."

As his team explained it, the human body requires many thousands of different types of molecules to function and thrive. It also needs the symbiotic help of a teeming number of microorganisms -- bacteria, fungi and viruses -- that live inside people and on their skin.

However, these molecules and germs aren't static: Their composition changes as people age, according to the new report published Wednesday in the journal Nature Aging .

Snyder and the paper's lead author Xiaotao Shen were prompted to conduct their analysis when they noticed that the risk for many illnesses don't rise in a steady, linear fashion over time.

Instead, risks jump sharply at certain time periods: For example, the big jump in risk for Alzheimer's disease that occurs after 60.

Snyder and Shen had already studied the aging of organs, the immune system and metabolism in a group of 108 people. In their new study, the they analyzed blood and other biological samples provided by this group every few months over the span of several years.

The Stanford team focused on changes in crucial molecules -- for example, genetic material called RNA, certain proteins and metabolites -- as well as the participants' microbiome, which is the assorted germs that live within and on a person.

In total, the researchers tracked age-related changes in more than 135,000 different molecules and microbes, for a total of nearly 250 billion distinct data points.

In 81% of cases, changes in molecular or microorganism abundance and composition over time were non-linear, meaning that sharp changes happened at certain periods in life more than others.

The mid-40s and the early 60s were two points where these peaks in changes were most pronounced, Synder and Shen found.

At first, the researchers assumed that menopause -- which many women go through in their late 40s -- was skewing the results, but it turned out that the same changes were occurring for men during this time.

"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. Identifying and studying these factors should be a priority for future research," said Shen, who was a postdoctoral scholar at Stanford when he worked on the study. He's now an an assistant professor at Nanyang Technological University Singapore.

So, how could the molecular and microbial changes he and Synder spotted affect your health?

Many of the shifts could raise a person's odds for heart trouble in the 40s and the 60s, while other changes could dampen the power of the immune system as people enter their 60s, they reasoned.

In a person's 40s, changes occurred among molecules that could influence the health of the skin and muscle, as well as the metabolism of substances such as alcohol, caffeine and fat, according to the study.

During the 60s, changes occurred that further affected skin and muscle, as well as caffeine metabolism. But changes took place that also affected carbohydrate metabolism, as well as the integrity of the immune system, the heart and the kidneys.

According to the researchers, there's a growing consensus that there can be a big difference in a person's chronological age and biological age.

Not all of the molecular or microbiome changes were due to genetics, the team theorized. For example, because a person's 40s can often be a stressful time, people tend to drink more -- and that might influence the molecular changes that occur around alcohol metabolism at that time.

All of that means that individuals can help minimize any deleterious effects of molecular-level change in their 40s and 60s, Snyder and Shen said, simply by living in a healthy way.

"I'm a big believer that we should try to adjust our lifestyles while we're still healthy," Snyder said.

More information

Find out more about your microbiome at the National Human Genome Research Institute.

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