Adult female brains appear, on average, a few years younger than same-aged male brains, a new study finds. For men and women of the same chronological age, the algorithm guessed the women were actually three years younger. "It's not that men's brains age faster - they start adulthood about three years older than women, and that persists throughout life", he added. This in turn may help explain why women tend to experience less of a decline in thinking abilities as they age, the researchers wrote in the study, published today (Feb. 4) in the journal Proceedings of the National Academy of Sciences.
For the objective of the study, the researchers made more than 200 men and women participants, ranging in age from 20 to 82 years, go through PET scans to measure oxygen and glucose flow in their brains.
The study exclusively focused on brain metabolism, or the brain's ability to use glucose-aka sugar-to function.
One change involves the way the brain uses sugar and oxygen to fuel its efforts, Goyal said.
Goyal and his co-authors explained that their findings are consistent with evidence from previous studies indicating that, compared with the male brain, the female brain displays less cerebral blood flow loss after puberty, more brain glycolysis (or breaking down of glucose) in young adulthood and decreased loss of certain types of cerebral gene expression over time.
In reverse, they trained the algorithm on women's data and applied it to men's.
Then they reversed the process and had the computer estimate a person's age based on brain metabolism data. Scientists wanted to map how the brain ages over time, and compare the chronological and metabolic ages of men and women.
"Brain metabolism might help us understand some of the differences we see between men and women as they age", Goyal said.
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This can cause problems later in life and scientists hope to one day slow it down with state-of-the-art drugs or brain therapy. Sex differences during brain development, then, might set the stage for the overall trajectory of brain aging. Even among the youngest participants, women's brains are younger than men's.
"What this tells us is that sex has an effect on how the brain ages, metabolically speaking", he said. Similarly, the algorithm judged men's brains to be an average 2.4 years older than their actual age.
More studies are now needed to better understand this brain-age difference and whether it affects the risk of age-related brain disease, such a Alzheimer's.
"It's not that men's brains age faster", said Goyal.
As the researchers say, the extent of brain decline varies considerably between individuals.
For the new study, the researchers analyzed PET scans of 205 adults, all cognitively normal. But Roberta Diaz Brinton, who studies brain aging at the University of Arizona, has a more optimistic take on the results. "We're being very cautious in not speculating on what this means in terms of downstream dementia and so forth".
The U.S. National Institute on Aging has more about the aging brain.
In fact, brain metabolism might have little to do with diseases like Alzheimer's or dementia, said Dr. Gayatri Devi, a neurologist with Lenox Hill Hospital in New York City.