We all know our body starts to 'break down' as we age, but that shift might be more sudden than we previously thought.
A study by Stanford Medicine reveals many of the body’s molecules and microorganisms starkly rise or fall in numbers at two specific times — ages 44 and 60.
Researchers assessed thousands of different molecules involved in ageing, in people from age 25 to 75, as well as their microbiomes — the bacteria, viruses and fungi that live inside us and on our skin.
They found 81 per cent of the molecules and microbes do not shift in a gradual, chronological fashion. Instead, we undergo two periods of rapid change during our life span.
The number of molecules related to cardiovascular disease showed significant changes at both ages, and those related to immune function — our ability to fight diseases — changed in people in their early 60s, the research published in the journal Nature Aging revealed.
'We’re not just changing gradually over time; there are some really dramatic changes,' said Michael Snyder, chair of genetics and the study’s senior author.
'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 research team was inspired to look at the effects of molecular and microbial shifts after observing that the risk of developing age-related conditions like Alzhiemer's disease and cardiovascular disease, sees a sharp rise in midlife, rather than a steady one.
Data was used from 108 people to better understand the biology of aging.
Participants' blood and other biological samples were analysed every few months over several years; the scientists tracked 135,000 age-related changes in different molecules, including RNA — which carries genetic information — proteins and metabolites, as well microbiome.
They found that thousands of molecules and microbes undergo shifts in their abundance, either increasing or decreasing.
Aound 81 per cent of the molecules they studied showed went through extreme changes at specific ages.
When they looked for clusters of molecules with the largest changes in amount, they found these transformations occurred the most in two time periods: when people were in their mid-40s, and when they were in their early 60s.
The large cluster of changes in the mid-40s was somewhat surprising to the scientists.
At first, they assumed that menopause or perimenopause was driving large changes in the women in their study, skewing the whole group.
But they found the shift was happening in men in their mid-40s, too.
'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 Dr Xiaotao Shen, a former Stanford Medicine postdoctoral scholar, and now an assistant professor at Nanyang Technological University Singapore.
In people in their 40s, significant changes were seen in the number 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.
It’s possible some of these changes could be tied to lifestyle or behavioral factors that cluster at these age groups, Dr Snyder said.
For example, dysfunction in alcohol metabolism could result from an uptick in alcohol consumption in people’s mid-40s, often a stressful period of life.
The team plans to explore the drivers of these clusters of change.
But the findings suggest individuals must pay attention to their health in their 40s and 60s, the researchers said.
That could look like increasing exercise to protect your heart and maintain muscle mass, or decreasing alcohol consumption.
'I’m a big believer that we should try to adjust our lifestyles while we’re still healthy,' Dr Snyder said.
