Scientists have just found a new distinction between the brains of the two sexes: Age-related brain changes occur more slowly in women than in men.
Average structural differences between the sexes represent the real thing.
This latest research indicates that the female brain, on average, appears to be about three years younger than the male brain of the same age when it comes to brain metabolism.
According to the researchers, this difference could be why women tend to stay mentally sharp for longer than men.
“We are beginning to understand how various factors related to sex could affect the trajectory of brain aging and how this could influence the vulnerability of the brain to neurodegenerative diseases,” says Manu Goyal of the Mallinckrodt Institute of Radiology at the University School of Washington and co-author of the work collected by PNAS magazine. “Brain metabolism could help us understand some of the differences we see between men and women as they age.”
Scientists had already established that age-related decrease in gray matter volume occurs more rapidly in male brains than in female brains. Gene expression in the brain has also been shown to change more rapidly in older men than in women, resulting in a reduced ability to build and break down molecules in the male brain.
These evidences suggest a form of neoteny (preservation of the juvenile state in the adult organism) in the female brain, but no one had analyzed the metabolism of the brain until now.
As we age, glucose use changes in the brain. In children, a metabolic process called aerobic glycolysis has a high incidence. It is associated with brain development, increasing in sync with synaptic growth and formation.
This process slows down as we approach adulthood and continues to slowly decline. The brain still uses sugar for cognitive function, but aerobic glycolysis plateaus reach a very low level around age 60.
Obviously, the exact age can vary from person to person, but to determine if there are sex differences at that point, the research team performed positron emission tomography (PET) scans on 205 people: 121 women and 84 men, out of 20 to 82 years of age.
The researchers looked at the flow of oxygen and glucose in their brains to determine the proportion of glucose that was being allocated for aerobic glycolysis. They then fed a machine learning algorithm with male sample data to establish a relationship between age and brain metabolism.
Using this as a baseline, the experts asked the algorithm to estimate the ages of the women based solely on their brain metabolism data. He calculated that the women were, on average, 3.8 years younger than they actually were.
Then they did it in reverse. The algorithm revealed that the men were an average of 2.4 years older than their actual age.
And, what’s more interesting, this difference was seen even in people as young as 20 years old.
“It’s not that men’s brains age faster, they start adulthood about three years later than women, and that persists throughout life,” Goyal said.
” What we don’t know is what it means. I think this could mean that the reason women don’t experience as much cognitive decline in later years is because their brains are indeed younger, and we are currently working on a study to confirm this. “, ends.
Reference: Persistent metabolic youth in the aging female brainManu S. Goyal, Tyler M. Blazey, Yi Su, Lars E. Couture, Tony J. Durbin, Randall J. Bateman, Tammie L.-S. Benzinger, John C. Morris, Marcus E. Raichle, and Andrei G. Vlassenko. PNAS published ahead of print February 4, 2019 DOI: https://doi.org/10.1073/pnas.1815917116
