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• Posted July 10, 2025

'Old' Brains Increase Risk Of Death, Alzheimer's

They say age is all in your mind — and that might literally be true, a new study reveals.

People with “young” brains — brains aging more slowly than their actual age — are much less likely to die or develop Alzheimer’s disease than those with “old” brains suffering from accelerated aging, researchers reported July 9 in the journal Nature Medicine.

Results show that having an extremely aged brain nearly triples a person’s risk of dying during a roughly 15-year period.

At the same time, people with extremely youthful brains had a 40% lower risk of early death, researchers found.

In other words, the biological age of the brain plays an outsized role in determining how long a person has left to live, said senior researcher Tony Wyss-Coray, director of the Knight Initiative for Brain Resilience at Stanford Medicine.

“The brain is the gatekeeper of longevity,” he said. “If you’ve got an old brain, you have an increased likelihood of mortality. If you’ve got a young brain, you’re probably going to live longer.”

Previous research has shown that a person’s body can age from wear-and-tear more rapidly that what is reflected by their birth date. Essentially, a person’s biological age can be older than their calendar age.

For this study, researchers analyzed blood samples from nearly 44,500 people 40 to 70 participating in the UK Biobank, a large-scale health research project in the United Kingdom.

Researchers used proteins found in the blood samples to estimate the biological age of 11 distinct organs or organ systems for each person, including the brain.

About 6% to 7% of participants had “extremely youthful” brains, and a similar proportion had “extremely aged” brains.

Overall, researchers found that any organ’s biological age increased its likelihood of disease.

For example, an extremely aged heart increased risk of abnormal heart rhythm or heart failure, and aged lungs increased COPD risk.

But the association between an aged brain and Alzheimer’s was particularly powerful – more than three times that of a person with a normally aging brain, researchers said.

On the other hand, people with youthful brains had a quarter of the Alzheimer’s risk linked to brains that were aging normally, the study found.

In other words, someone with a biologically old brain is about 12 times as likely to be diagnosed with Alzheimer’s as a person the same age with a biologically young brain, researchers concluded.

These results could open the door to new medical screenings that could determine people’s risk for various diseases based on the biological age of their organs, Wyss-Coray said.

Future research also could figure out whether existing approved drugs might restore organ youth before people develop a disease based on that aging organ, he added.

“This is, ideally, the future of medicine,” Wyss-Coray said. “Today, you go to the doctor because something aches, and they take a look to see what’s broken. We’re trying to shift from sick care to health care and intervene before people get organ-specific disease.”

Wyss-Coray plans to commercialize the blood sample test, working with companies to get it on the market within a few years.

“The cost will come down as we focus on fewer key organs, such as the brain, heart and immune system, to get more resolution and stronger links to specific diseases,” he said.

More information

The Mayo Clinic has more on biological versus chronological age.

SOURCE: Stanford Medicine, news release, July 9, 2025