We don’t age gradually throughout our lives. Instead, we go through rapid and accelerated bursts of ageing, typically at age 44 and then at 60.

The findings were part of new research published in Nature Aging. These results could explain why certain health conditions, like cardiovascular diseases and musculoskeletal problems, occur at particular ages.

We age in dramatic bursts at 44 and 60Peter Finch – Getty Images
‘We’re not just changing gradually over time. There are some really dramatic changes,’ Prof Michael Snyder, director of the Center for Genomics and Personalised Medicine at Stanford University and senior author of the study, said to The Guardian.

The study

Stanford University researchers tracked age-related changes in 108 volunteers between the ages of 25 to 75. More than 5,400 skin, mouth and nose swabs and blood and stool samples were submitted at intervals of a few months, over anywhere between one and nearly seven years. In total, 135,000 different microbes (bacteria, fungi and viruses living in the gut and skin) and molecules (RNA, proteins) were assessed.

The results

Scientists found that most of the organisms and compounds did not change gradually as time passed, but instead transformed most dramatically when people were in their mid-40s and early 60s.

Mid-40s changes

In the mid-40s, this first wave of changes occurred in molecules connected with cardiovascular disease and the ability to process caffeine, alcohol and lipids. The transformations were unexpected, and were initially assumed to be linked to hormonal changes occurring during perimenopause skewing results for the age group, but it was then found that similar spikes happening to men in the same age group.

‘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,’ Dr Xiaotao Shen, a former postdoctoral scholar at Stanford medical school and first author of the study, told The Guardian.

Mid-60s changes

In the second stage, changes occurred in molecules linked to immunity, kidney function and carbohydrate breakdown. Skin and muscular-ageing molecules also underwent shifts at both age periods. These findings are in line with previous evidence that there is a rapid, sharp increase of some diseases after a certain age, such as Alzheimer’s after age 60.

‘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’, Prof Snyder continued.

There is a likelihood that lifestyle or behavioural changes could impact these changes. For example, increased alcohol in the mid-40s could influence alcohol metabolism. Snyder therefore suggests that ‘we should try to adjust our lifestyles while we’re still healthy’, such as increasing strength training to combat molecular changes that cause muscle loss.