They found that dramatic changes occur in our molecules and microbiomes during our 40s and 60s that could influence disease risk, underscoring the importance of taking care of our health during these key life stages.
We look in the mirror every day, and while we are aware of the signs of aging – especially when comparing ourselves to our previous photos – we have the feeling that the changes are gradual. However, if you have ever felt like everything in your body starts to fail at the same time, it may not be just your imagination, as a new study from Stanford School of Medicine reveals that many of our microorganisms and molecules undergo dramatic changes in numbers at two crucial times in life: during our 40s and in our 60s.
The researchers analysed thousands of different molecules in people aged between 25 and 75, as well as their microbiomes – the bacteria, viruses and fungi that live on our bodies and on our skin. They found that the abundance of most of these molecules and microbes does not change gradually with age, but rather occurs in two periods of rapid change, on average around the age of 44 and 60. The findings have been published in Nature Aging.
“Our bodies don’t change gradually over time; there are really dramatic changes,” said Michael Snyder, a professor of genetics and senior author on the paper. “It turns out that the mid-40s are a time of significant change, as is the mid-60s. And this applies to any type of molecule you’re looking at.”
These significant changes likely influence our health, as notable alterations in the number of molecules related to cardiovascular diseases were observed in both age groups, and those related to immune function showed changes in people around 60 years old.
Four ‘types of aging’ identified
Snyder and his team were inspired to study the speed of molecular and microbial changes by the observation that the risk of developing many age-related diseases does not increase gradually over time. For example, the risk of Alzheimer’s and cardiovascular disease increases dramatically in old age, compared with a more gradual increase in people under age 60.
The researchers used data from 108 people they have followed to better understand the biology of aging. Previous studies of this same group of volunteers revealed the existence of four ‘types of aging’, showing that the kidneys, liver, metabolism and immune system age at different rates in different people.
In the new study, they looked at participants who donated blood and other biological samples every few months over several years. The scientists tracked different types of molecules in these samples, such as RNA, proteins and metabolites, as well as changes in the participants’ microbiomes. The researchers identified age-related changes in more than 135,000 different molecules and microbes, amassing a total of nearly 250 billion data points.
They found that thousands of molecules and microbes experienced changes in their numbers, either increasing or decreasing. About 81% of the molecules studied showed nonlinear fluctuations, meaning they changed more at certain ages than at others. By identifying the groups of molecules with the largest changes in numbers, they found that these transformations occurred primarily in two periods: when people were in their 40s and in their 60s.
In people around 40 years of age, significant changes were observed in molecules related to the metabolism of alcohol, caffeine and lipids, cardiovascular diseases and skin and muscles.
While much research has focused on how certain molecules increase or decrease with age and how biological age can differ from chronological age, few studies have looked at the rate of biological aging. The fact that so many dramatic changes occur in one’s 60s is not surprising, Snyder said, since many risks for diseases and other age-related phenomena increase at that point in life.
The large cluster of changes in the 40-somethings surprised the scientists. At first, they assumed that menopause or perimenopause was driving large changes in the women in the study, skewing the entire group. But when they separated the study group by sex, they found that the changes also occurred in men in their 40s.
“This suggests that although menopause or perimenopause may contribute to the changes seen in women in their 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,” Shen said.
Changes that can influence health and disease risk
In people in their 40s, significant changes were seen in the amount of molecules related to alcohol, caffeine and lipid metabolism; cardiovascular disease; and skin and muscle. In those in their 60s, changes were related to carbohydrate and caffeine metabolism, immune regulation, kidney function, cardiovascular disease, and skin and muscle.
Some of these changes may be related to lifestyle or behavioral factors that cluster in these age groups, rather than being driven by biological factors, Snyder said. For example, dysfunction in alcohol metabolism could be the result of increased alcohol consumption in people in their 40s, an often stressful life stage.
The team plans to explore the causes of these changes. But regardless of their causes, the existence of these changes highlights the importance of paying attention to health, especially in our 40s and 60s, the researchers said. This could involve increasing exercise to protect the heart and maintain muscle mass at both ages, or cutting back on alcohol consumption in our 40s as the ability to metabolize alcohol declines. “I strongly believe that we should try to adjust our lifestyle while we are still healthy,” Snyder concludes.
