Women seem to have a cognitive edge over men—at least when it comes to the brain’s relative youthfulness. New research suggests that women's brains stay energized well into old age, making their brains appear about three years younger than men's of the same chronological age.
When we're kids, our brains produce more fuel, in the form of glucose, to promote growth. But as we age, our brains need less fuel to function. Despite the fact that the average adult of either sex produces and uses less energy than a younger individual, scientists from Washington University School of Medicine in St. Louis have found that women’s brains continually create more fuel than men’s whether an individual is 25 or 82, Quartz’s Katherine Ellen Foley reports.
To gauge such sex-based differences, the team captured brain imaging scans of 121 women and 84 men aged 20 to 82, according to the study published in Proceedings of the National Academy of Sciences. Next, Ian Sample explains for the Guardian, the scientists put this information into an algorithm designed to predict a brain’s age.
In the first set of experiments, the system was trained to predict men’s ages based on metabolic data—like oxygen and glucose levels—from positron emission tomography, or PET scans, NPR’s Jon Hamilton explains. Once the algorithm was able to accurately assess these ages, the researchers switched out the data, using metabolic information from women’s brains instead of men’s. Compared to the set of male brain scans, the program underestimated women’s brain ages by an average of 3.8 years. The team then trained the algorithm to predict women’s ages instead. When men’s brain scans were put into this new system, the program estimated them to be 2.4 years older than their actual ages.
Researchers remain uncertain why such metabolic differences exist and what implications they could have for cognitive decline in members of both sexes. As Manu Goyal, a radiologist and neurologist at Washington University who led the study, tells NPR’s Hamilton, the team has considered such factors as hormones and genetics. Goyal tells Dennis Thompson of HealthDay News that differences in brain development during puberty could “set the stage for how [men and women are] going to age subsequently.”
"It's not that women's brains seem to age slower than men's," Goyal adds. "Rather, it seems that women's brains start off at a younger age when they reach adulthood, and they keep that throughout the remainder of their adulthood, basically buying them a few extra years."
Previous studies have found that aging women often exhibit stronger reasoning, memory and problem-solving skills than males of the same age. But it’s unclear whether this trend is related specifically to metabolism or to a different aspect of brain function. Moving forward, the researchers note in a statement, the team plans on tracking a group of adults over time to gauge whether individuals with “younger-looking brains” are less likely to face cognitive problems as they age.
“This might mean women are a little bit more resilient to certain aspects of brain aging in general, but it could also introduce certain vulnerabilities,” Goyal tells Thompson. “Having a younger brain for longer could make the brain more vulnerable to certain things as well. We're being very cautious in not speculating on what this means in terms of downstream dementia and so forth."