Women’s Metabolic Brain Age Is Around Three Years Younger Than Men’s

New research suggests women have the competitive edge over men—at least when it comes to the brain’s relative youthfulness, as represented by a measure called metabolic brain age.
Writing for HealthDay News, Dennis Thompson reports that scientists from Washington University School of Medicine in St. Louis have found that women’s brains age more slowly than men’s. On average, the researchers note in Proceedings of the National Academy of Sciences, females boast a sizable metabolic advantage over men of the same chronological age, with women’s brains appearing around three years younger than those of similarly aged male counterparts.

To gauge such sex-based differences, the team captured brain imaging scans of 121 women and 84 men aged 20 to 82. Next, Ian Sample explains for the Guardian, the scientists put this information into an algorithm designed to predict a certain brain’s age.

In the first set of experiments, the system was trained to predict men’s ages based on metabolic data garnered from the brain scans. Once the algorithm was able to accurately assess these ages, the researchers switched out the data, inputting metabolic information from women’s brains instead of men’s. Based on the existing male-centric framework, the program estimated women’s brain ages to be an average of 3.8 years younger than their actual ages.

Next, the team trained the algorithm to predict women’s ages. 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.

According to NPR’s Jon Hamilton, the surprising findings—which remained consistent across the board regardless of a subject’s specific age—built on positron emission tomography, or PET scans, of participants’ brains. These tests, in turn, revealed how well a brain in question metabolized glucose, or transformed sugar into the energy needed to power the cranium.

Typically, the amount of energy a brain needs shifts throughout life, with children requiring the highest levels of “fuel” and adults producing less and less as they mature. Despite the fact that the average adult of either sex produces and uses less energy than a younger individual, the study shows women’s brains continually create more fuel than men’s whether an individual is 25 or 82, notes Quartz’s Katherine Ellen Foley.

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; speaking with HealthDay News’ Thompson, Goyal further explains 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.”

source: Smithsonian.org By Meilan Solly

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