Women's Brains Age Better Than Men's. Scientists Just Discovered the Reason Why

Mar. 15, 2025

A close-up view of a doctor’s hand pointing at brain scan images displayed on a digital tablet.Photo:Tom Werner/Getty

Tom Werner/Getty

A new study out of the University of California San Francisco indicates that women’s brains might be better suited for aging than men’s — and it’s all thanks to a “silent” chromosome.Females have two X chromosomes, and, for a long time, scientists believed the second X chromosome — referred to as a “sleeping” or “silent” chromosome — was essentially pointless.Anew study from UCSF, however, found that aging actually “awakened” the second X chromosome in 20-month-old genetically modified female mice, which are the equivalent of a 65-year-old human. This then expressed genes that helped to strengthen the brain’s connections and increased cognition.Stock image of a woman speaking to a doctor.nensuria/Getty“In typical aging, women have a brain that looks younger, with fewer cognitive deficits compared to men,” saidDena Dubal, MD, PhD, a professor of neurology and the David A. Coulter Endowed Chair in Aging and Neurodegenerative Disease at UCSF.“These results show that the silent X in females actually reawakens late in life, probably helping to slow cognitive decline.”The paper, which appears in the March 5 edition ofScience Advances, shares that the second “silent” chromosome expressed around 20 genes, most of which had a role in aiding brain development.“Aging had awakened the sleeping X,” Dubal said.Researchers believe this could be an explanation for how the human female brain reacts to aging.“We immediately thought this might explain how women’s brains remain resilient in typical aging, because men wouldn’t have this extra X,” said Margaret Gadek, a graduate student in UCSF’s combined MD and PhD Medical Scientist Training Program and first author of the paper.Neurologist reviews patient’s brain MRI scan - stock photo.SDI Productions/GettyNever miss a story — sign up forPEOPLE’s free daily newsletterto stay up-to-date on the best of what PEOPLE has to offer​​, from celebrity news to compelling human interest stories.With this discovery, scientists believe that they can now do research into improving mental and cognitive abilities in aging.“Cognition is one of our biggest biomedical problems, but things are changeable in the aging brain, and the X chromosome clearly can teach us what’s possible,” Dubal said, noting that they will be looking into “interventions” that might “amplify” genes to assist with brain function during aging.

A new study out of the University of California San Francisco indicates that women’s brains might be better suited for aging than men’s — and it’s all thanks to a “silent” chromosome.

Females have two X chromosomes, and, for a long time, scientists believed the second X chromosome — referred to as a “sleeping” or “silent” chromosome — was essentially pointless.

Anew study from UCSF, however, found that aging actually “awakened” the second X chromosome in 20-month-old genetically modified female mice, which are the equivalent of a 65-year-old human. This then expressed genes that helped to strengthen the brain’s connections and increased cognition.

Stock image of a woman speaking to a doctor.nensuria/Getty

nensuria/Getty

“In typical aging, women have a brain that looks younger, with fewer cognitive deficits compared to men,” saidDena Dubal, MD, PhD, a professor of neurology and the David A. Coulter Endowed Chair in Aging and Neurodegenerative Disease at UCSF.

“These results show that the silent X in females actually reawakens late in life, probably helping to slow cognitive decline.”

The paper, which appears in the March 5 edition ofScience Advances, shares that the second “silent” chromosome expressed around 20 genes, most of which had a role in aiding brain development.

“Aging had awakened the sleeping X,” Dubal said.

Researchers believe this could be an explanation for how the human female brain reacts to aging.

“We immediately thought this might explain how women’s brains remain resilient in typical aging, because men wouldn’t have this extra X,” said Margaret Gadek, a graduate student in UCSF’s combined MD and PhD Medical Scientist Training Program and first author of the paper.

Neurologist reviews patient’s brain MRI scan - stock photo.SDI Productions/Getty

SDI Productions/Getty

Never miss a story — sign up forPEOPLE’s free daily newsletterto stay up-to-date on the best of what PEOPLE has to offer​​, from celebrity news to compelling human interest stories.

With this discovery, scientists believe that they can now do research into improving mental and cognitive abilities in aging.

“Cognition is one of our biggest biomedical problems, but things are changeable in the aging brain, and the X chromosome clearly can teach us what’s possible,” Dubal said, noting that they will be looking into “interventions” that might “amplify” genes to assist with brain function during aging.

source: people.com