Artificial intelligence has offered scientists a new window into how the human body ages, revealing that different organs can follow very different ageing timelines and that some of these changes may eventually be detected through a blood test.
Researchers from the CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences and the Ludwig Boltzmann Institute for Network Medicine developed AI-based “tissue clocks” that estimate the biological age of individual organs from microscopic tissue images.
The findings, published in Nature Medicine, were based on more than 25,000 images covering 40 tissue types.
AI reads signs of ageing in human tissues
The researchers used data from the Genotype-Tissue Expression Project (GTEx), which contains tissue samples from 983 people. The samples included organs and tissues such as the brain, heart, lungs, pancreas, skin and intestine.
Researchers analysed 25,712 high-resolution images, representing around 480 million individual image tiles. Using advanced computer vision models, they found that age was the strongest factor influencing tissue appearance across all 40 tissue types.
The team then developed tissue clocks capable of estimating the biological age of individual organs based on their microscopic structure.
The clocks had an average prediction error of 4.9 years and were also able to capture tissue-specific signs of disease and ageing.
Organs do not age at the same pace
The study found that ageing follows different patterns across the body. The lungs, kidneys, pancreas and adrenal glands showed signs of accelerated ageing as early as the ages of 20 to 40.
Other tissues followed more complex ageing patterns, while the uterus showed a particularly pronounced change around menopause.
The researchers also identified links between tissue ageing and health conditions. Kidney failure was associated with accelerated ageing signals across several tissues, while diabetes showed particularly strong effects in the pancreas.
The tissue clocks were also associated with established markers of ageing, including shorter telomeres, tissue pathology and the number of chronic diseases affecting an individual.
Blood could reveal ageing inside organs
Because collecting tissue samples can be invasive and impractical, researchers explored whether the information could be obtained from blood.
They matched blood-based gene expression profiles with tissue age measurements from the same individuals and developed predictors capable of estimating tissue-specific biological age using blood samples.
The blood-based models identified ageing patterns associated with conditions including Alzheimer’s disease, Crohn’s disease, cystic fibrosis, vasculitis, diabetes and stroke.
In people with Alzheimer’s disease, the strongest ageing signal was found in the brain, while Crohn’s disease was associated with accelerated ageing across the gastrointestinal tract.
AI could support future disease monitoring
The researchers say the findings demonstrate that ageing is not simply determined by chronological age. Different organs may age differently depending on systemic and tissue-specific factors.
The ability to identify organ-specific ageing patterns from a blood sample could eventually contribute to less invasive ways of monitoring organ health and disease progression.
However, the research represents an early step rather than an immediately available diagnostic test. Further work will be needed to determine how these AI-based tissue clocks perform in clinical settings and whether they can reliably support disease detection or monitoring.
The study nevertheless demonstrates how combining artificial intelligence, tissue imaging, gene expression and clinical information could provide a more detailed picture of ageing and its relationship with disease.