Have you ever wondered why elderly women seem much more mentally sharp than men of the same age? It’s not because women live longer—though they do, on average—or because men’s brains age faster than women. Scientists are trying to get to the bottom of that puzzle, and have discovered a new clue in the form of glucose.
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Researchers at the Washington University School of Medicine, in St. Louis, wanted to learn more about the metabolism of aging brains. What they found was that, on average, female brains have a metabolism several years younger than their actual age would indicate. Men’s brains? A couple years older than their actual age.
The brain is a very demanding organ, in terms of metabolism—that’s how efficiently and quickly it breaks chemicals down to use them. What the brain is breaking down is glucose, a form of sugar, which is energy both to young children and to all of our brains. A portion of the brain’s glucose goes to a process called aerobic glycolysis, which helps the brain develop—basically, it keeps the brain young. The larger the portion of glucose going to that, the younger the brain might act.
The researchers in this study noticed that the percentage of glucose used for aerobic glycolysis shrinks with age. So they tested 205 people, ranging from age 20 to 82, and both men and women, to see what’s going on with their brain-sugar. An algorithm was developed by using that data to figure out the relationship between glucose levels and actual age. But there was a large variance by gender: women, it seems, use more glucose later in life than men.
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Men’s brains, from the start of adulthood, seem to be about three years older, mentally speaking, than women’s brains, and that gap simply continues as a person ages. The researchers were quick to note, in the study’s press release, that while this gap is significant, it isn’t the only factor that determines the sprightliness of a brain.
Still, this research lines up with other studies. This one, from 2001, found that women over the age of 85 test significantly better than men of the same age on tests measuring cognitive speed and memory—despite the fact that the men tested in that study had higher levels of education than the women. Maybe it’s all down, like so many things in life, to sugar.