Scientists believe the brain metabolisms of women appear to take longer to slow than men’s, which could explain why they tend to stave off cognitive decline for longer.
Over time, the brain changes how it uses glucose—or sugar—as a process called aerobic glycolysis drops to low levels by the time we reach around the age of 60. Scientists wanted to map how the brain ages over time, and compare the chronological and metabolic ages of men and women.
The team found women’s brains appeared to be three years younger metabolically—known as neotenous—on average than men.
The researchers carried out their study by analyzing PET scans of 205 people with healthy brains aged between 20 to 82 years old in order to use a sample representative of the human adult lifespan. The participants were taking part in six studies across the Washington University School of Medicine.
They created algorithms to calculate the metabolic ages of the participants, which they compared to their chronological ages. They found women’s brains were more youthful as young adults, and the trend continued into old age.
Pointing to existing research, the team surmised that women’s brains could be free from neurocongitive decline for longer for a number of reasons. One explanation could be that the genes involved in energy use could be less impacted by age in women. Or that women don’t experience the same loss of blood flow in the brain after puberty than men. Studies in rodents, meanwhile, have suggested estrogen could make the brain more adaptable to change.
Further research is needed to uncover whether the neoteny of women helps them to avoid neurodegenerative diseases.
Dr. Manu Goyal, senior author of the study and assistant professor of neurology and neuroscience at Washington University School of Medicine, provided some context for the findings, and explained in a statement: “it’s not that men’s brains age faster—they start adulthood about three years older than women, and that persists throughout life.
“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 effectively younger, and we’re currently working on a study to confirm that.”
Goyal continued that while the differences between the brain age of men and women is “significant,” it is “nowhere near as big a difference as some sex differences, such as height.”
Next, the team will investigate why older women tend to score better on brain tests in areas including reason, memory and problem solving than their male counterparts of the same age.
Dr. Michael Bloomfield, Honorary Consultant Psychiatrist and the head of the Translational Psychiatry Research Group at University Colleged London, U.K., told Newsweek: “It is important that we don’t draw unjustified conclusions from this study in terms of differences between men and women, but that doesn’t take away the need to ask these questions.
“Ultimately, many studies keep showing that the differences between any two people tend to be negligible, and that the power of this type of study is in looking at large numbers of brain scans.”
Last year, a separate study delving into a similar topic concluded that depression was associated with a faster decline in cognitive abilities, including memory and decision making skills. The review of 34 studies was published in the journal Psychological Medicine.