On a morphological level, research has already shown that men's and women’s brains are different. A recent study from Washington University School of Medicine in Saint Louis has shed light on metabolic differences between the two. Indeed, sex appears to have an influence on brain aging...

In humans, normal aging is associated with a decrease in brain metabolism. We know that the brain metabolizes glucose, but the way it’s used changes as we age. As babies and children, our brain draws on this "fuel” to develop and mature. This process is called aerobic glycolysis. The remaining sugar is burned to fuel the daily tasks of thinking and acting. As adolescents and adults, a significant amount of glucose is still used for these processes, but as we age, the amount stabilizes at much lower quantities (around the age of 60).

For their study, Manu Royal and his team examined 84 men and 121 women ages 20 to 82. Each participant received a PET (positron emission tomography) scan. This medical imaging technique involves injecting a solution with a radioactive tracer than can be tracked throughout the body. The flow of oxygen and glucose can then be measured (particularly in the brain). For all subjects, the researchers were able to determine the proportion of sugar used for aerobic glycolysis in various brain areas. Using this data, they established an automatic learning algorithm to determine the brain’s metabolic age.

According to the authors: “This provides a single measure of accelerated or decelerated metabolic brain aging based on multiparametric and multiregional metabolic data, which thereby allows us to determine whether females differ from males with respect to their aging brain.”

On average, the algorithm predicted that women's brains were 3.8 years younger than their chronological age. But the calculation predicted the brain ages of the men to be 2.4 years older than their actual age. The researchers noted that this youthful tendency for women's brains was detectable even amongst the youngest participants. According to the authors, men’s brains don’t age more quickly, but are rather three years older than women's brains when they enter adulthood, and this disparity remains throughout life.

The fact that the female brain remains metabolically younger could explain why women suffer less from cognitive decline than men. In seniors, women tend to perform better on memory and problem-solving tests than men of the same age.