Saturday, July 28, 2012

Women's brains age faster, possibly due to stress

Stress is not just a psychological thing: it can greatly impact physiology, because the body acts differently under stressful conditions. For example, the hormone cortisol is produced by many mammals during feelings of stress. A so far unproven hypothesis states that stress can lead to faster ageing, and scientists from the University of California in Berkely set out to investigate whether there is any truth to it. They found that the brains of women age faster, and that stress is likely increasing the pace.

To assess the differences between men and women, the researchers set out to assess the activity of as much as 13.000 genes. Basically, they set up a transcriptome, which is the combined activity of all genes in our cells. Such measurements help to discern general patterns, but require a lot of input data. The researchers set up experiments to assess the genetic activity in brains of 55-year-old males and females.

After looking at which genes differ the most in activity between men and women, the scientists noted that the observed pattern in women makes their brains age at a faster pace when compared to men. The difference in ageing, indirectly observed by measuring genetic activity, was especially apparent in an area of the prefrontal cortex, which is involved with conscious thoughts and decisions. Because women have an, on average, longer life span than men, the findings are quite remarkable, but it is known that not all organs in the body age at the same rate.

An additional finding was that there is a rather large variance between individual women when it comes to genetic ageing. It shows that being male or female is not the sole determinant of brain ageing. There are likely some environmental factors involved, of which the scientists think stress is the most likely to explain the observed differences. One of the reasons for this hypothesis is a study performed with monkeys, revealing that stress can induce similar age-related changes in the transcriptome.

According to the scientists, their study can help explain cognitive decline or the onset of neurodegenerative diseases associated with increasing age. Some of the genetic findings are associated with such medical events, and are therefore more likely to occur in women. This warrants more study: trials should be set up to prospectively assess the effect of stress on ageing, with neurodegenerative diseases and cognitive decline as clinical endpoints.

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