Dormant X Chromosome May Explain Why Women's Brains Age Better Than Men's

A UCSF study finds that a 'silent' X chromosome activates in older women, bolstering brain function and cognitive resilience.

Researchers at the University of California, San Francisco discovered that the second, previously dormant X chromosome in women reactivates late in life.
This reactivation expresses genes that improve brain connections and cognitive function, potentially explaining why women experience less cognitive decline than men with aging.
The study, conducted on genetically modified mice, identified around 20 genes activated by the dormant X chromosome, including PLP1, which supports myelin production in the brain.
Artificially increasing PLP1 levels in male and female mice improved memory and learning, suggesting possible therapeutic interventions for aging-related cognitive decline.
Analysis of human brain tissue confirmed elevated PLP1 levels in older women, and researchers are exploring ways to amplify these gene effects in both sexes.