Do not worry yet about the stress that shrinks your brain

Relax: A new study shows that people with a higher "stress hormone" tend to have a smaller brain – but that does not mean that one causes the other.

The study, published today in the journal Neurology, reported lower brain volumes and worse memories in people with higher than average cortisol levels, commonly known as stress hormone. But any media coverage that warns that stress is going to shrink your brain is premature. "At the moment, all we can say is that A is associated with B, we really can not say anything about causality," says Sudha Seshadri, professor of neurology at the Science Center from the University of Texas Health in San Antonio and lead author of the study. .

"The results are fascinating," says Bruce McEwen, neuroscientist at Rockefeller University in New York, who did not participate in the research. But, he adds, "cortisol is the visible part of the iceberg. There is a lot going on underneath. "

Cortisol is a hormone that the body pumps in response to a number of different stressors, such as sudden stress, psychological stress or chronic inflammation. And this is not the first time scientists have linked these elements to brain changes: other studies have associated excessively high levels of cortisol with reduced brain regions, such as the parts of the brain involved in memory . Decreased brain can signal neurological or cognitive impairment. While this does not necessarily mean that brain cells are dying, it could mean that these valuable cells are losing their support systems, says McEwen. "It's a sign that things are not going well."

In today's study, a team of researchers led by Seshadri and Justin Echouffo-Tcheugui, an assistant professor at Johns Hopkins University, examined the all brain, in more than 2,000 apparently healthy people. To find them, the research team turned to Framingham Heart Study, a large-scale, three-generation study that has been monitoring a Massachusetts community since 1948. The researchers took blood samples on participants to measure their cortisol levels and test their memory. reasoning and attention. The researchers also imagined the brain of the study participants to look for differences in brain volumes as well as changes in the white matter isolating the biological cabling of the brain.

Participants were divided into three different groups with low, medium and high levels of cortisol. And the researchers found that people with the highest levels of cortisol tended to have lower memories and attention, as well as lower brain volumes, especially women. The high cortisol group also showed signs of white matter injury, which the study authors believe could contribute to differences in memory and attention: if you weaken the isolation, the signals do not circulate as efficiently in the wiring.

Nevertheless, McEwen recommends readers do not conclude too quickly that since cortisol is involved, stress is to blame. That's right, surprising and stressful events can make your glands start to eject cortisol. But other insults can do the same thing: the body uses cortisol to calm inflammation, for example. Thus, chronic inflammation may also cause an increase in cortisol. "He's a cop if you just add that to the word stress," says McEwen. ("When you read the newspaper, did you see anything about the stress?", Asks the author of the study, Echouffo-Tcheugui.The answer is no, not before the reference section .)

It is possible that it is cortisol that triggers changes in the volume of the brain. This has already been seen, says McEwen. But it is also possible that inflammation – if there is one – plays a role in the white matter lesions detected by the researchers. "Yes, it's possible, there could be a number of factors like this," Seshadri admits.

McEwen hopes the team will continue to dig Why some people had higher levels of cortisol than others, and what else could affect their brains, and the researchers hinted at plans to do it. "It's a good step in the right direction," says McEwen. "Below, there is a lot of biology that has yet to be explored."