You've heard of being "young at heart", but what about young in the brain?
Women tend to outlive men and stay mentally sharp longer, and a new study out Monday could explain why: female brains appear on average about three years younger.
The findings still need to be confirmed in follow-up studies. Then, the researchers entered women's brain metabolism data into the algorithm and directed the program to calculate each woman's brain age from its metabolism.
Further research is needed to uncover whether the neoteny of women helps them to avoid neurodegenerative diseases.
"What we don't know is what it means", senior study author Dr. Manu Goyal, an assistant professor of radiology at Washington University School of Medicine in St. Louis, said in a statement. The brain still uses sugar for cognitive function, but aerobic glycolysis plateaus at a low level usually by the time people are in their 60s. When people are younger, they devote more glucose to a metabolic process called "aerobic glycolysis", which is thought to help with brain development and maturation, including brain-cell growth.
They are now following a group of adults as they age to see whether people with younger-looking brains are less likely to develop cognitive problems.
Women have younger brains than men the same age, according to new research.
The study enrolled 121 women and 84 men, who underwent PET scans to measure brain metabolism, or the flow of oxygen and glucose in their brains. They used the women's data as a baseline, and estimated the men's ages based exclusively on their metabolism data. They trained a machine-learning algorithm to find a relationship between age and brain metabolism by feeding it the men's ages and brain metabolism data.
The initial study was conducted by first training the machine learning algorithm using men's ages and brain metabolism data. It calculated that the men were an average of 2.4 years older than their actual age.
"It's not that men's brains age faster - they start adulthood about three years older than women, and that persists throughout life", Goyal said.
Interestingly, the gap between men and women's brain ages was detectable even in young adults in their 20s.
Goyal said that while the differences between the brain age of men and women was "significant", it was "nowhere near as big a difference as some sex differences, such as height".
One theory is that hormones might begin shaping brain metabolism at a young age, setting females on a pattern that is more youthful throughout their lives, compared to men.