Medicine

Scans show women's brains remain youthful as male brains wind down

Scans show women's brains remain youthful as male brains wind down

It was already known that men's brains shrink faster with age than women's, but the new results suggest their brain metabolism is different too.

Men's brains may be larger but women hold a trump card in the mental battle of the sexes: their grey matter behaves as if it were three years younger.

The study, which focused on how the brain uses sugar, involved 121 women and 84 men ranging in age from 20 to 82 years.

"We're just starting to understand how various sex-related factors might affect the trajectory of brain ageing and how that might influence the vulnerability of the brain to neurodegenerative diseases", said neuroscientist Manu Goyal of the Mallinckrodt Institute of Radiology at Washington University School of Medicine in St. Louis.

The brain runs on sugar, but how the brain uses sugar changes as people grow and age.

A computer algorithm found women used a higher proportion of glucose to develop their brain, showing their brains were younger.

The researchers were looking at the flow of oxygen and glucose in their brains to determine the proportion of the glucose that was being allocated to aerobic glycolysis.

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"It's not that women's brains seem to age slower than men's", Goyal said.

It turns out that female brains tend to age more slowly, researchers report. 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.

Brain aging is associated with a gradual decline in brain metabolism.

The researchers also performed the analysis in reverse: They trained the algorithm on women's data and applied it to men's.

It may explain why older men see a bigger drop in their memory and language skills than women, whose younger brains may protect them from forgetfulness for longer.

A study basing age on metabolism rather than birth date found an average 3.8 year difference between the two. However, it's possible that it could explain why "women don't experience as much cognitive decline [as men] in later years, . because their brains are effectively younger". Only a tiny amount goes in by the time people are in their 60s.

Interestingly, the gap between men and women's brain ages was detectable even in young adults in their 20s.