Scientists pinpoint the moment we start feeling old

One moment, you’re in your 20s and feeling spry. Next thing you know, your back is killing you, your knees are creaking, and a hangover lasts three days instead of just one. What gives?

Ageing is a natural part of life, but many people talk about feeling suddenly old, particularly in their late 30s and early 40s. Scientists have now discovered why that happens.

A new study by researchers at Stanford Medicine found that we do not age at a steady pace, but instead, there seem to be two stages during which our molecules and microorganisms undergo rapid shifts.

These rapid changes occur in our mid-40s and again in our 60s. More precisely, we experience these on average at age 44 and age 60.

Michael Snyder, professor of genetics and senior author of the study, said: “We’re not just changing gradually over time; there are some really dramatic changes.

“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.”

The researchers highlighted that the changes likely had an effect on our health, with the number of molecules related to cardiovascular disease showing significant changes at both stages. Meanwhile, the molecules related to immune function changed in people in their early 60s.

Using data from 108 people, the team set out to understand the biology of ageing by analysing blood and other biological samples over the span of several years. Samples were taken every few months and used to track a number of different molecules, as well as shifts in the microbiome.

It was revealed that thousands of molecules and microbes undergo changes, either increasing or decreasing, with around 81% changing more at certain ages. The transformations took place the most when people were in their mid-40s and early 60s.

While it was expected that significant changes would occur in older age, the large shift in molecules came as a surprise to the scientists, according to Stanford University. They initially theorised that menopause or perimenopause was the cause of large changes in the women in the study, but later found that the shift took place in men as well.

Xiaotao Shen, former Stanford Medicine postdoctoral scholar and first author of the study, said: “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.”

Major changes were seen in the molecules related to alcohol, caffeine and lipid metabolism in people in their 40s. The scientists acknowledged that some of the changes could be linked to lifestyle or behavioural factors that tend to start at these age groups, such as increased alcohol consumption due to stress.

However, researchers believe the molecular changes are cause for people to pay more attention to their health, particularly at these ages.

This includes making lifestyle changes like exercising more to increase heart health and maintain muscle mass or drinking less alcohol in your 40s, because the body’s ability to metabolise alcohol slows down.

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