A new study from Washington University School of Medicine in St. Louis finds that women's brains appear to be about three years younger than men's of the same chronological age, metabolically speaking.
As adulthood progresses, people get less of the glucose pumped through the brain, reducing the energy funneled into the process.
A machine-learned algorithm showed that women's brains were on average about 3.8 years younger than their chronological ages. Evolutionary theorists have predicted that females might have more youthful brains (neoteny) as compared with males, but until now findings in support of this theory have been limited to postmortem transcriptional analysis, some of which is contradictory.
Their brains appear nearly four years younger than men's on average, a study suggests.
Scientists have observed that people's brains change both in structure and function as they grow older. The relative sprightliness was detectable even among the youngest subjects, who were in their twenties.
Still, more research is needed to better understand brain aging overall and to help prevent or delay neurodegenerative diseases, including Alzheimer's, which are "a major growing problem in the United States and elsewhere", he said.
Still, Goyal noted that the difference between men and women's brain ages was relatively small compared with other well-known sex differences, such as height.
To confirm that the female-male difference in metabolic brain age was not specific to training on male data, the researchers flipped the process, training the algorithm on female data only.
Goyal and his colleagues believe that the greater youthfulness in the female brain might give a degree of resilience to aging-related changes.
Goyal explained that while this could mean that women were more likely to be capable of learning and creative in their later years, it may also raise the risk of developing Alzheimer's disease in women.
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For the new study, the researchers analyzed PET scans of 205 adults, all cognitively normal.
The researchers suspect that women gain this advantage during puberty, Goyal said. Having a younger brain for longer could make the brain more vulnerable to certain things as well. "What we don't know is what it means", he added.
Did sex affect brain age? "Differences in how a female's and a male's brain develops across puberty sets the stage for how they're going to age subsequently".
Accordingly, it is important to understand the factors that influence brain aging, particularly in the context of an aging population.