Do We Age in Bursts? What's Behind the 44-and-60 Claim

Whether we age in two distinct bursts, around 44 and around 60, is currently an open question. A widely publicised Stanford study described exactly that in 2024 ¹. In summer 2026, a reanalysis co-authored by the original researchers themselves showed that the statistical methods used can produce such "bursts" even where none exist ². The journal has since added an editor's note to the study ¹.

At first that sounds like a letdown. It is actually rather good news, both for science and for anyone who wants to do something for their health. Because there is no birthday on which the window for prevention opens or closes.

What did the study on ageing bursts show?

Stanford researchers followed 108 adults aged 25 to 75 over several years, regularly analysing their blood, stool and swabs ¹. They measured an enormous range of things: gene activity, proteins, metabolites, blood fats and the bacteria living on different parts of the body.

Their finding: only a small share of these molecules changed steadily with age. Most seemed to change in jumps, with two striking clusters around ages 44 and 60 ¹. Around 44, the changes mainly involved fat and alcohol metabolism and markers of heart and blood vessel health; around 60, they involved the immune system, sugar metabolism and the kidneys ¹.

Two further details were interesting. The patterns looked similar in women and men, so menopause alone could not explain them ¹. And the authors themselves noted that shifts in alcohol and caffeine metabolism might simply reflect changing habits ¹.

The study made headlines around the world. The idea was catchy: ageing as a staircase rather than a ramp. And it matched a feeling many people know.

Why is the study being re-examined?

Because it turned out that the staircase may come, at least in part, from the method of analysis. To find trends among countless individual measurements, the researchers first smoothed their data and then used a "sliding window" to look for age ranges with particularly many changes ¹.

A team led by John Quackenbush tested this combination more closely. What they found: feed the methods pure random data and waves and peaks appear as well ². Where the peaks land depends partly on how many people of each age are in the study. And a key control test in the original study had been run in the wrong order; done correctly, the peaks at 44 and 60 disappear ².

What is remarkable is who co-wrote this reanalysis: the two lead authors of the original study ². In July 2026, Nature Aging published an official note stating that the reliability of these analyses is currently in question and that corrections are being assessed ¹.

Does this mean ageing is gradual after all?

Not necessarily. The reanalysis does not prove that there are no phases of faster change. It only shows that these methods alone cannot reliably detect them ². And it is not only about this one study: the sliding-window method has been used in many ageing studies in recent years, and their "waves" should now be checked more carefully too ². For research, this is a valuable learning moment and a push to safeguard analyses even more rigorously against chance.

The study itself also had an important limitation that got lost in much of the coverage: most participants were followed for just under two years. So the "bursts" came from comparing different people of different ages, not from following individuals through their 40s or 60s ¹. The authors themselves wrote that confirming this would require observation over decades ¹.

So here is what we can honestly say:

Well established	Still open
Ageing changes many processes in the body at once.	Whether there are fixed "burst years" that apply to everyone.
People age at different speeds.	Whether the peaks at 44 and 60 are real or a statistical artefact.
Risk factors in midlife shape later health.	Whether targeted prevention at exactly these ages achieves more.

Can you influence your biological age?

Early studies suggest so. In a small randomised pilot trial, healthy men aged 50 to 72 followed an eight-week programme of adjusted diet, exercise, sleep and relaxation practices plus certain supplements ³. Afterwards, their biological age, estimated from chemical changes to their DNA known as an epigenetic clock, was a little over three years lower than in the control group ³.

That is an encouraging signal, but not yet proof. The group was small and male-only, the control group received no programme at all, and biological age was measured with a single clock ³. Whether this actually prevents disease remains open. Larger studies are the next step.

If you are curious about your own biological age, find out more about the speak23 Biological Age test and in our article Biological age: what it tells you, and what it doesn't.

When is prevention most worthwhile?

Now, whatever your age. The strongest evidence here comes not from molecular research but from large population data. The Lancet Commission on dementia prevention, for example, names several risk factors that matter especially in midlife, including high blood pressure, high LDL cholesterol and excess weight ⁴. Overall it lists 14 modifiable factors across the life course, from education to good hearing to physical activity. According to its modelling, together they could account for up to 45% of dementia cases worldwide: a theoretical potential, but an impressive one ⁴. Its conclusion: risk factors should be lowered early enough and kept low, and the earlier the better ⁴.

This fits one of the Commission's most encouraging observations: in high-income countries, the age-specific risk of dementia has fallen over recent decades, probably partly because vascular risks such as high blood pressure and smoking are better treated ⁴. Prevention works, not only in the lab but across whole societies.

In everyday terms:

• Know your numbers regularly: blood pressure, blood fats and blood sugar are simple measurements that tell you a lot, in your 30s just as in your 60s. The speak23 Core Health blood test gives you an overview.
• Watch for changes, not birthdays: tracking your values over the years shows your own trajectory, whether ageing happens in bursts or gradually.
• Don't underestimate the basics: physical activity, not smoking, a healthy weight and well-controlled blood pressure are among the modifiable factors with the broadest impact ⁴.

What does this mean for the medicine of tomorrow?

The story of the "bursts at 44 and 60" shows how research works at its best: an exciting idea is published, others test it, and the original researchers help correct it themselves. For preventive medicine built on measurement, this kind of care is the foundation.

And perhaps the message in the end is even better than the original one. Our bodies do not follow a fixed timetable with two stops where everything tips over. They change all the time, and they respond all the time to how we live. In an ageing society, that is a liberating insight: health in later life is not decided on two key dates but through many small decisions over decades. There is no appointment you can miss. There is only the next good moment to start.