Even though women live longer than men, their brains seem to age faster. The reason? Possibly a more stressful life.
As people age, some genes become more active while others become less so. In the brain, these changes can be observed through the transcriptome, a set of RNA molecules that indicate the activity of genes within a population of cells.
When Mehmet Somel, a computational biologist at the University of California at Berkeley, and his colleagues compared the transcriptome of 55 brains, they found that the pattern of gene activation and deactivation that occurs with aging appeared to progress faster in women.
“This was just the opposite of what we’d originally expected,” says Somel.
He says that because women have longer lives, his group had expected to see slower or later aging-related brain changes. “But it fits everyday observations on aging. Not all organs within an individual age at the same rate.”
Somel’s team compared the expression of more than 13,000 genes in four brain regions. In the superior frontal gyrus, which has been associated with self-awareness, the researchers found 667 genes that were expressed differently in men and women. Of those, 98 percent were skewed toward faster aging in women.
Some of these gene changes have been linked to general cognitive decline and degenerative disease.
The researchers noted that about half of the women showed accelerated age-related changes. They say that this suggests that the cause was environmental rather than simply biological.
“A higher stress load could be driving the female brain towards faster aging-related decline,” Somel says. His team found tentative support for that theory in a study of monkeys, where stress induced similar changes to their brain transcriptome.
Cyndi Shannon Weickert, a researcher at Neuroscience Research Australia, says the Somel group’s findings are interesting, but the connection to stress is speculative. She notes that stress is only one possible cause of these effects. Inflammation, for example, might lead to similar changes.
This article was produced by New Scientist magazine.