Study Reveals Different Organs Follow Different Ageing Timelines

Ageing is unavoidable, yet it is far from uniform.

It is easy to imagine ageing as a smooth, linear progression, each day, week and month quietly carrying us towards our Golden Years. However, fresh research indicates it may instead resemble a mosaic or patchwork quilt, shaped by hormonal signals.

A new study published in Nature Aging charted structural shifts in dozens of human tissues. It found that different areas of the body appear to operate on remarkably varied ageing timetables.

Certain tissues begin changing quickly during our 30s. Others stay relatively unchanged until around menopause in female bodies. Some seem to experience two separate phases of accelerated ageing.

Put simply, there may not be one universal “ageing process” occurring across the entire body. Different organs and body systems may follow their own schedules – and organ systems can affect one another.

PathStAR maps structural tissue ageing

To investigate this, a team led by computational biologist Sanju Sinha at the Sanford Burnham Prebys Medical Discovery Institute in California created a computational tool called PathStAR. It analyses the microscopic structure of tissues shown in standard pathology images.

Instead of being trained to estimate someone’s chronological age, the system assessed the physical architecture of changes within tissue.

The team used PathStAR to examine images from more than 25,000 post-mortem tissue samples, obtained from 970 donors aged 21–70 and representing 40 distinct tissue types.

“This is a public dataset used by hundreds of groups, but nearly everyone uses the molecular data,” Sinha says, referring to the Genotype-Tissue Expression Project, which collected the samples.

“There are tens of terabytes of imaging data that have gone nearly untouched.”

Arteries and reproductive tissues follow distinct schedules

Arteries were among the body’s earliest agers, undergoing their most rapid structural changes during the 30s. This corresponded with pathology records showing that early arterial plaque formation rose most sharply in that decade before flattening out later.

Those whose arteries displayed more accelerated structural ageing were also more likely to have atherosclerosis, in which plaque accumulates inside arteries and hardens them.

So, although your 30s may seem rather early to count as “old age”, your arteries seemingly do not wait.

The reproductive system, meanwhile, looked very different.

In female bodies, the uterus and vagina stayed comparatively stable in early adulthood, before undergoing their most pronounced structural shifts in the early to mid-50s – around the menopausal transition.

These changes included characteristics such as tissue atrophy and a thinner endometrium, the lining of the uterus, in keeping with the effects of falling oestrogen levels.

The ovaries showed another pattern. Rather than changing consistently over time, ovarian tissue experienced one burst of structural ageing between about 35 and 40, followed by another between roughly 55 and 60, during the postmenopausal period.

Researchers detected this pattern in the tissue’s physical structure, even though similar studies of gene expression and DNA methylation failed to replicate the same two peaks.

Biphasic ageing across organs may reflect hormonal signals

A comparable two-stage pattern of ageing was also found in other organs.

Of the other 14 tissues for which the researchers could establish high-confidence trajectories, nine displayed what they termed “biphasic” ageing. This involved two phases of accelerated structural change, generally in the 30s and 50s.

They included organs with no apparent connection to reproduction: the oesophagus, stomach, colon and small intestine. In male bodies, the prostate and testis followed this ageing pattern as well.

These organs therefore appear to age in synchrony, and the links are not restricted to organs located close together.

People with accelerated structural ageing in the colon and oesophagus were also more likely to show it in the prostate, although the synchronisation seemed to extend much more widely.

“More than half the tissues we studied followed the structural aging of the ovaries,” Sinha says, “so we see the ovaries as a kind of pacemaker for whole-body aging.”

Hormones may hold the answer, as they circulate through the body as signalling molecules rather than being limited to reproductive systems.

“The steepest drops [in hormone signaling capacity] occurred in gastrointestinal tissues,” the researchers report, “consistent with the known expression of estrogen receptors throughout the digestive epithelium and their role in mucosal barrier maintenance.”

It therefore makes sense that the gut may age at rates similar to those of the uterus or prostate.

Across these organs, accelerated structural ageing shared the same signature: greater inflammation alongside reduced energy production, cell proliferation and cellular quality-control systems.

The researchers suggest that a better understanding of how organs and systems age could ultimately reshape how we approach interventions designed to slow ageing. Instead of viewing ageing as a single, even process, it may be more sensible to focus on specific organs during the periods when they are most susceptible.

“By developing therapies to protect reproductive aging, we see the potential to protect multiple other organs and increase the overall healthspan,” Sinha says.

There are several important caveats to the study. For one, the samples were post-mortem, and a person’s cause of death could influence the apparent age of their tissues, particularly for younger people.

The researchers also recognise that change is not invariably equivalent to ageing: “Not all age-associated changes imply functional decline; some may reflect adaptive remodeling or neutral variation,” they note in their paper.

The analysis further relied on relatively broad age ranges, meaning it cannot pinpoint precisely when tissue changes start in any individual.

Even so, the work appears to suggest that our bodies probably do not have only one biological clock steadily ticking away.

They may have dozens – and not all of them are showing the same time.

The study has been published in Nature Aging.

This article was fact-checked by Rachel Garner and edited by Clare Watson. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.