ARI SHAPIRO, HOST:
A new study published today in the Proceedings of the National Academy of Sciences says a woman's brain tends to remain youthful long after a man's brain has started to slow down. NPR's Jon Hamilton reports.
JON HAMILTON, BYLINE: A person in their 60s may have the body of someone much younger. And scientists at Washington University in St. Louis thought the same thing might be true of a person's brain. So they studied the brains of more than 200 adults. Special scans revealed each brain's metabolism, something that decreases with age. Manu Goyal a neuroradiologist says the team was hoping...
MANU GOYAL: We could perhaps predict the age of the brain using that metabolic information.
HAMILTON: The scientists had a computer study how metabolism changed with age. Then they reversed the process and had the computer estimate a person's age using information on brain metabolism. And Goyal says the approach worked.
GOYAL: It's quite accurate. It's about maybe 90 percent accurate.
HAMILTON: Even so, for some people, there was a big difference between their brain age and their chronological age. And Goyal says the team wondered whether this difference was more pronounced in men or women.
GOYAL: When we looked at sex, when we looked at males versus females, we found in fact that females had a younger brain age relative to males.
HAMILTON: About four years younger on average. Goyal says it's not clear why women's brains remain youthful.
GOYAL: It makes us wonder, are hormones involved in influencing brain metabolism and how it ages?
HAMILTON: Or is it something else, like genetics? Goyal says higher metabolism may give female brains an edge when it comes to learning and creativity in later life. But he says all that youthful vigor also could have a downside.
GOYAL: It might also set up the brain for certain vulnerabilities.
HAMILTON: Like Alzheimer's disease. But Roberta Diaz Brinton, who studies brain aging at the University of Arizona, has a more optimistic take on the results.
ROBERTA DIAZ BRINTON: It's great news for many women.
HAMILTON: Brinton says the great news is for the majority of women whose brain metabolism remains high as they age. Her research shows these women have a low risk of developing Alzheimer's. But Brinton says around menopause, a small proportion of women experience a dramatic drop in brain metabolism.
BRINTON: This transition is actually an energy transition in the brain.
HAMILTON: Brinton says women who develop metabolic problems tend to carry a gene that increases the risk for Alzheimer's. They're also at risk for Type 2 diabetes.
BRINTON: It's those women who will begin to develop the pathology of Alzheimer's disease earlier.
HAMILTON: Brinton says as brain metabolism decreases in these women, there's an increase in the clumps of sticky protein associated with Alzheimer's.
BRINTON: This is a process that starts very early in the aging process in some women, and we can intervene.
HAMILTON: How? Brinton says it's a lot like preventing diabetes. The key is diet, exercise and drugs that help the body and brain metabolize sugar. Jon Hamilton, NPR News.