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Metabolic Brain Age: Sex Differences Identified

OLDER women commonly outperform men in their age group in tests of reasoning, memory, and problem-solving, but the reason for this is currently unknown. Now, the latest research is offering vital clues to help solve this puzzle, showing that men’s brains appear older than their biological age, while the reverse is true for their female counterparts.

Researchers from Washington University in St. Louis, Missouri, USA, studied 205 participants (121 women, 84 men) between the ages of 20 and 82. To assess brain metabolism in each of the participants, a PET scan was used to measure the cerebral flow of oxygen and glucose and the rate of sugar used during aerobic glycolysis was then derived. Once analysed, the resulting metabolic data showed that women’s brains were, on average, 3.8 years younger than their chronological age. The reverse was true for men, whose brains were found to be, on average, 2.4 years older than their biological age. These significant differences between the sexes was not only seen when comparing men and women of advanced age; in fact, even the study’s youngest participants showed this same disparity.

Further study is required to better understand ageing-related changes to the brain, but the researchers hypothesise that differences in cerebral blood flow, hormones, and gene expression may make the female brain more resistant to the negative effects of advancing age. “This could mean that the reason women don’t experience as much cognitive decline in later years is because their brains are effectively younger,” suggested Dr Manu Goyal, Washington University, St. Louis.

A separate phase of this study also sought to identify whether brains with signs of beta-amyloid plaque, a protein that promotes the development of Alzheimer’s, appeared older. Results showed that this was not the case, suggesting that beta-amyloid plaque may not affect brain metabolism until a certain level of neurodegeneration has taken place. The researchers are planning further experiments, including looking in more detail at the effects of brain metabolism on the development of complex neurodegenerative diseases.