Stress may cause women's brains to age prematurely
Despite the fact that women live longer than men, their brains often age faster. Mehmet Somel, a computational biologist at the University of California, Berkeley, and his colleagues investigated that situation. They published their findings on July 26 in New Scientist Magazine.
As individuals age, some genes become more active while others become less active. In the human brain, these changes can be observed through the “transcriptome,” which are a group of RNA molecules that indicate the activity of genes within a population of cells. The researchers compared the transcriptome of 55 male and female brains of different ages; they were surprised to find that the pattern of gene activation and deactivation that occurs with aging appeared to progress faster in women than in men. This was particularly apparent in an area of the pre-frontal cortex. “This was just the opposite of what we’d originally expected,” noted Dr. Somel. He noted that given the fact that females have a longer lifespan, they had expected to see slower or later age-related changes in their brain. “But it fits everyday observations on aging. Not all organs within an individual age at the same rate,” he explained.
The investigators compared the expression of more than 13,000 genes in four brain regions. In one region, the superior frontal gyrus, they found 667 genes that were expressed differently in men and women during aging. Of those, 98% were skewed towards faster aging in women. Some of these gene changes have previously been linked to general cognitive decline and degenerative disease. They noted that sex differences were not uniform among all women. About half the women showed accelerated age-related changes. The researchers note that this suggests that the cause may be environmental rather than simply biological.
Dr. Somel explained, “A higher stress load could be driving the female brain towards faster ageing-related decline.” 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 from Neuroscience Research Australia in Sydney reviewed the results. She noted that the initial results are interesting; however, the connection to stress is speculative. She explained that it would help to know whether the subjects had other medical conditions at the time of death that might have affected their brain transcriptome. She added that stress is only one possible cause of these effects. Inflammation, for example, might lead to similar genetic changes.
The investigators are planning further reason on the topic. They next plan to test the effects of stress on the brain transcriptome of rodents. He would also like to compare stress and age-related neurodegenerative disease patterns across cultures, where female roles vary. He explained, “If the mechanism we hypothesise is correct, any policy that ensures equality in opportunity and empowers women could improve future health.”
Reference: New Science Magazine