In a study published in the journal “Nature Aging,” scientists recorded structural changes in dozens of human tissues and found that different parts of the body age according to surprisingly different schedules.
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Some tissues change rapidly from the age of thirty, others hardly change until menopause, and some organs age in two distinct leaps.
In other words, there is no single common aging process occurring at the whole-body level. On the contrary, individual organs or systems have their own timelines, and different organ systems can influence each other, writes “Science Alert.”
What did the scientists do?
To find this out, a research team led by bioinformatics specialist Sanju Sinha from the Sanford Burnham Prebys Medical Research Institute in California developed a computational system called “PathStAR.” The system examines the microscopic structure of tissues in standard pathological anatomy images.
Instead of simply determining human age, the system assessed physical changes in tissue structure.
The scientists applied the “PathStAR” method to more than 25,000 tissue samples taken from 970 deceased donors (aged 21 to 70), covering 40 different tissue types.
“This is a publicly available dataset used by hundreds of scientific groups, but almost all of them analyze molecular data,” says S. Sinha, referring to the Genotype-Tissue Expression project, during which the samples were collected. “However, tens of terabytes of imaging data have remained almost untouched until now.”
Which ages earliest?
Arteries were among the earliest aging parts of the body – the fastest stage of their structural changes was recorded already in the fourth decade of life. These observations are supported by data collected by pathologists: the most intense formation of arterial plaques occurs between the ages of 30 and 40, after which this process slows down.
Faster aging of arterial structure is directly linked to atherosclerosis – the hardening of blood vessels due to plaque buildup inside them.
So although talking about old age at thirty may seem early, your arteries apparently do not wait.
The situation in the reproductive system is completely different.
In early youth, the condition of the uterus and vagina remains unchanged, but in the mid-fifties, approaching menopause, these organs undergo the greatest structural transformation.
These changes include signs such as tissue atrophy and thinning of the uterine lining, which is directly related to decreasing estrogen levels.
The ovaries showed a different dynamic. Instead of changing gradually, two aging surges were observed in ovarian tissue structure: the first around 35–40 years, and the second at 55–60 years, i.e., after menopause.
Researchers identified this pattern by assessing the physical tissue structure, although gene expression or DNA methylation analyses did not reveal such distinct aging peaks.
A similar two-stage aging model was demonstrated by other organs as well.
Of the remaining 14 tissue types whose developmental trajectories scientists were able to determine very reliably, a so-called “biphasic” aging was recorded. In this case, two periods of faster structural changes usually occurred in the fourth and sixth decades of life.
These included organs that seemingly have nothing to do with reproduction: the esophagus, stomach, large and small intestines. In the male body, the same aging pattern was mirrored by the prostate and testes.
It appears that these organs age synchronously, and the connections are not limited to adjacent body parts.
Individuals who exhibited faster aging of the large intestine and esophagus often showed the same processes in the prostate, but this synchronization seems to be on an even broader scale.
“More than half of the tissues we studied followed the ovarian aging pattern,” says S. Sinha. “Therefore, we consider the ovaries as a kind of whole-body aging stimulator.”
“The main driver of these changes is hormones. They act as messengers throughout the body, not limited to the reproductive system.
“The most pronounced weakening of hormonal connection was recorded in digestive tract tissues,” the researchers say. “This confirms the fact that estrogen receptors, distributed throughout the digestive system epithelium, are vital for maintaining the protective mucosal barrier.”
So it makes sense that the intestines age at a similar pace as the uterus or prostate.
Aging of different organs is characterized by similar features: declining energy production, slower cell renewal, and deteriorating quality control, alongside which inflammatory processes intensify.
According to scientists, new knowledge about aging of individual organs could fundamentally change prevention strategies. Instead of trying to stop the whole-body process, it would be more effective to strengthen specific organs precisely when they are most vulnerable.
“By developing therapies that protect the reproductive system, we see an opportunity to help other organs and extend overall healthy lifespan,” says S. Sinha.
The study was published in the journal “Nature Aging.”
