Women’s brains age differently

Why are women more likely to retain mental clarity in old age? Specialists at the University of California at San Francisco have found the answer: the “silent” X chromosome, which remains inactive for most of life, begins to work over the years, protecting the brain from age-related changes.

Each person has two sex chromosomes: males have XY and females have XX. For a long time it was believed that one of the female X-chromosomes, located in the cell nucleus in the form of the so-called Barr’s calf, practically does not participate in the vital activity of the body. However, scientists have found that over time, this “reserve” chromosome comes into play and triggers processes that help maintain cognitive abilities.

Analyzing the activity of genes in the brain of aging female mice, the researchers found that at an age equivalent to 65 human years, the “sleeping” X chromosome begins to produce about 20 genes, most of which are associated with the development of the nervous system. Among them, the PLP1 gene, responsible for strengthening the myelin sheath of nerve fibers, which improves signal transmission in the brain, stands out.

Additional experiments confirmed that when PLP1 levels were artificially increased in old mice of both sexes, their memory and learning abilities improved. This means that the mechanism that protects the female brain can potentially be activated in males as well.

The next step will be to study this process in older women. The first assays performed on donor brain samples have already shown that women have higher levels of PLP1 than men.

“Brain aging is one of the most pressing problems in modern medicine. But we now know that it is not programmed once and for all. If we can find ways to activate the right genes, we may be able to slow cognitive decline in all people, regardless of gender,” commented the study authors.