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In A Nutshell
- Stanford scientists used blood proteomics from ~45,000 people to predict the biological age of 11 organs.
- Organs age at different rates — your brain might age faster or slower than your liver or heart.
- People with multiple “aged” organs faced sharply higher risk of disease and death — up to 8.3× higher for those with 8+ aged organs.
- A youthful brain and immune system combo offered the strongest protection, slashing death risk by more than half.
STANFORD, Calif. — A simple blood test might soon reveal whether your brain functions like a 30-year-old’s or a 70-year-old’s — and whether you’re likely to live a long, healthy life or face an early death. Stanford University researchers analyzed blood samples from nearly 45,000 people and discovered something surprising: organs age at wildly different speeds, and having a young brain and immune system could be your ticket to longevity.
People whose brains aged rapidly faced the same Alzheimer’s risk as those carrying the most dangerous genetic variant for the disease. On the flip side, those with younger brains had protection equal to carrying protective genes. Most striking of all, people with both young brains and immune systems had 56% lower odds of dying during the study.
Reading Your Body’s Age Through Blood
Stanford’s research team, led by Tony Wyss-Coray, PhD, a professor of neurology and neurological sciences, created what works like an age test for 11 major organs by measuring nearly 3,000 proteins in blood samples. When organs age or sustain damage, they leak specific proteins into the bloodstream — traces that reveal their condition. Scientists trained AI models to predict chronological age based on these protein patterns from each organ.
If someone’s predicted organ age exceeded their actual age, that organ was labeled “aged.” When it fell below, the organ was considered “youthful.” The method worked across 44,498 participants aged 40-70 from the UK Biobank, with researchers tracking them for up to 17 years to monitor disease development and deaths.
The findings, published in Nature Medicine, confirmed that organs don’t age in lockstep. Brain aging showed minimal correlation with other organs, proving that biological aging follows its own timeline in different body systems.
The More Aged Organs, The Higher Your Risk
Death risk climbed steeply with each additional aged organ. Those with 2-4 aged organs faced 2.3 times higher death risk. People with 5-7 aged organs saw their risk jump to 4.5 times normal. Most concerning were those with 8 or more aged organs. These individuals faced 8.3 times higher odds of death.
“More than 60% of people with 8+ extremely aged organs at blood draw died within 15 years,” researchers observed.
Brain aging proved especially critical among all organs tested. Beyond predicting death, it signaled increased risk for conditions far outside the brain, including heart failure and lung disease. This makes sense given the brain’s role as the body’s command center, controlling hormones, immune responses, and other vital functions through intricate signaling networks.
Your Lifestyle Shapes Your Organ Age
The research brought some good news: organ aging isn’t set in stone by genetics. Multiple lifestyle factors affected biological age across several organs. Smoking, heavy drinking, processed meat consumption, and poor sleep accelerated aging. In contrast, vigorous exercise, eating fish, and higher education levels correlated with younger organ profiles.
Several supplements and medications showed protective effects. Ibuprofen, glucosamine, cod liver oil, multivitamins, and vitamin C linked to younger biological ages in multiple organs, especially kidneys, brain, and pancreas. The hormone therapy Premarin, commonly prescribed for menopausal symptoms, correlated with younger immune, liver, and artery profiles.
Young Brain and Immune System: The Golden Combination
While aged organs generally meant higher death risk, the study revealed an important twist: not all youthful organs offered equal benefits. Surprisingly, people with young arteries actually showed increased death risk, and those with broadly youthful organs across many systems showed no survival advantage over normal agers.
Two organs, however, provided exceptional protection. People with young brains had 40% lower death risk, while those with young immune systems saw 42% lower risk. The combination proved especially powerful — individuals with both enjoyed the strongest protection from death.
“I expected many more organs to be linked to longevity, but our data suggest the immune system and brain are key,” lead author Hamilton Oh, PhD, tells StudyFinds. “After thinking more about it though, it makes intuitive sense. Both the brain and immune system control so many parts of our physiology – the brain through nerve branches that sprout from the spinal cord and the immune system through resident and migratory cells present in all tissues. These systems may be the guardians of our whole body.”
During the 17-year follow-up, only 3.8% of people with young brains and immune systems died, compared to 7.9% of normal agers. The brain-immune connection makes biological sense, as these systems constantly communicate and chronic inflammation speeds up aging throughout the body.
Brain aging stemmed largely from proteins produced by oligodendrocytes. These are cells that create myelin, the insulation around nerve fibers. This suggests white matter breakdown plays a central role in brain aging. The strongest marker was neurofilament light chain, already used in clinical trials to track brain degeneration.
The biological analysis showed that young brain aging correlated with preserved brain support structures, potentially because inflammatory factors caused less damage. Young immune aging linked to lower levels of inflammation-promoting proteins, indicating that controlling chronic inflammation helps maintain both systems.
Instead of viewing aging as an unstoppable, uniform decline, this research shows it’s an organ-specific process where the brain and immune system serve as crucial regulators of lifespan. For the first time, scientists can map which biological systems matter most for longevity — and many factors that influence organ aging appear modifiable through lifestyle choices.
Disclaimer: This report summarizes findings from a single peer-reviewed study published in Nature Medicine. The research uses advanced plasma proteomics to estimate biological organ age and its association with health outcomes in a large population. These results do not represent a diagnostic test or clinical guideline, and the organ age estimates are not yet available as an approved medical test. Readers should not interpret this information as medical advice. Always consult qualified healthcare professionals before making decisions about disease risk, supplements, medications, or lifestyle changes.
StudyFinds’ Q&A With Author Dr. Hamilton Oh
What motivated you to develop organ-specific aging models using blood proteomics instead of more established biomarkers like DNA methylation?
HO: Blood proteins are advantageous for many reasons. Proteins come from all tissues in the body and can be mapped to these tissues. They are the functional molecules that direct physiology. Some proteins are already measured in the clinic for annual checkup and are trusted by doctors to provide useful information about health. >95% of FDA approved drugs target proteins. The strongest DNA methylation predictor of mortality, GrimAge, is partly trained to predict the levels of ~10 plasma proteins previously linked to aging.
Your study highlights the brain and immune system as key regulators of lifespan. Were you surprised by how strongly these two systems stood out?
HO: I was definitely surprised. I expected many more organs to be linked to longevity, but our data suggest the immune system and brain are key. After thinking more about it though, it makes intuitive sense. Both the brain and immune system control so many parts of our physiology – the brain through nerve branches that sprout from the spinal cord and the immune system through resident and migratory cells present in all tissues. These systems may be the guardians of our whole body.
You found that having youthful arteries didn’t protect people and was sometimes linked to higher mortality risk. What’s your hypothesis for this counterintuitive finding?
HO: This was unexpected. It is possible that some processes that are beneficial in youth backfire in old age old. Maybe the artery proteins we are measuring are linked to these sorts of processes. It may also be that we are currently unable to measure other artery proteins that are more indicative of true youth. Future studies with advancing proteomic technologies should help bring clarity.
Were there any lifestyle factors or medications that surprised you by how much they affected organ aging?
HO: It was surprising that estrogen supplementation in women with early menopause had such strong effects on reducing immune age. Maybe this explains the previously shown links between estrogen supplementation and longer life in the UK Biobank. It also provides support for testing other drugs to determine their effects on immune age and longevity.
Many people want to know: if they have an “aged” organ profile, what can they realistically do to reverse or slow it?
HO: Exercise, diet, sleep, and low stress are tried and true ways to live longer and healthier. More research using these organ aging biomarkers is needed to find other interventions that can slow aging in specific organs.
In practical terms, how far away are we from a blood test like this being used in routine clinical checkups?
HO: Though I am confident these tests can predict certain diseases much better than what is routinely measured in the clinic today, it may take 10-20 years before they are fully incorporated. Most things that are currently measured in the clinic provide actionable insight. Though these tests might provide more information, what medical advice doctors can offer based on this is unclear until we have better drugs to prevent organ diseases. Organ age consumer tests for people who are curious about their organ should be available in 2-5 years.
What’s the next big question you want to tackle now that you have this organ-by-organ aging map?
HO: A major question is what does brain and immune system youth actually mean biologically? If we can figure this out, we may find new ways to keep our brains and immune systems youthful.
If you could give people one piece of practical advice based on these findings, what would it be?
HO: A healthy lifestyle goes a long way!
Paper Summary
Methodology
Researchers analyzed blood samples from 44,498 people aged 40-70 from the UK Biobank, measuring nearly 3,000 proteins. They identified proteins likely originating from specific organs based on gene expression data, then used machine learning to create aging models for 11 organs (brain, heart, liver, kidneys, lungs, muscle, pancreas, adipose tissue, arteries, intestines, and immune tissue). The team calculated “age gaps” by comparing predicted biological age to chronological age for each organ, tracking participants for up to 17 years to monitor disease onset and deaths.
Results
People with multiple aged organs showed sharply increased death risk, ranging from 2.3 times higher for 2-4 aged organs to 8.3 times higher for 8+ aged organs. Brain aging emerged as the strongest mortality predictor among individual organs. An aged brain tripled Alzheimer’s risk (similar to carrying one APOE4 gene), while a youthful brain reduced risk by 74%. People with young brains and immune systems had 56% lower death risk. The models successfully predicted future onset of heart failure, kidney disease, diabetes, and Alzheimer’s years before symptoms appeared.
Limitations
The study population consisted primarily of European ancestry participants, potentially limiting applicability to other ethnic groups. Researchers relied on cross-sectional age measurements rather than tracking aging rates over time. Organ protein classifications depended on tissue gene expression data, which may not perfectly reflect actual protein sources in blood. The findings need validation in diverse populations and with different proteomics technologies.
Funding and Disclosures
Research support came from the Stanford Alzheimer’s Disease Research Center, National Institute on Aging grants, Knight Initiative for Brain Resilience, Stanford Graduate Fellowship, and other institutional funding. Some authors have financial interests in companies developing aging-related technologies.
Publication Information
“Plasma proteomics links brain and immune system aging with healthspan and longevity,” published in Nature Medicine on July 9, 2025. The study was conducted by researchers from Stanford University’s departments of Neurology, Genetics, Psychology, and Wu Tsai Neurosciences Institute, led by Tony Wyss-Coray and Hamilton Se-Hwee Oh.
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