STRESS
September 9, 2014

Why Some Are Resilient in the Face of Stress

Some people seem resistant to stress, while others are susceptible to it. Researchers are starting to understand why.

Resilience — being able to bounce back from defeat or difficulty — is a popular buzzword these days among parents, educators and therapists. But the truth is that some people naturally seem to have a Teflon coating when it comes to stress, with stressful experiences just rolling right off them. Others are more like Velcro, with the stress just sticking.

Now we understand a little better why this difference exists, along with some clues into the genetics behind resilience.

The changes weren’t just visible on the outside — they were also apparent in the mice’s genes.

Mice were exposed to various stressful environments in the lab: A cage that tilted at random times, an unpredictable light-dark cycle, or confinement in a tight space. Then researchers looked at how the mice behaved as a result.

About 60% of the stressed mice seemed unfazed by the stressful experiences, and their behavior didn’t change much at all. But the other 40% of the mice were visibly stressed out by their experiences. They exhibited anxious behaviors like a preference for dark places over well lit ones, or the loss of interest in sugar water.

The changes weren’t just visible on the outside — they were also apparent in the mice’s genes. The mice which were susceptible to stress had lower levels of a molecule called mGlu2, particularly in a part of the brain called the hippocampus, which is known to be involved in the stress response.

The Rockefeller University researchers found that changes in this molecule were due to Epigenetic — those that occur not in the genetic code itself, but in the degree to which a gene is expressed. And what determines these changes is the types of experiences — whether traumatic, sad, or happy — we have throughout our lives.

“Like people, each animal has unique experiences as it goes through its life. And we suspect that these life experiences can alter the expression of genes, and as a result, affect an animal's susceptibility to stress,” said author Bruce McEwen.

“We have taken an important step toward explaining the molecular origins of this stress gap by showing that inbred mice react differently to stress, with some developing behaviors that resemble anxiety and depression, and others remaining resilient. ”

While it’s a little disheartening that life experiences could change the ways in which our genes function, it also means that the changes could be reversible. In fact, in previous research scientists found that when they increased mGlu2 levels in mice, the depressive symptoms brought on by stress quickly reversed.

Other research, in humans, has found that antidepressants, as well as physical exercise, can also go a long way in helping the brain return to a healthier state.

Research like this will be key to developing new treatments to reverse these changes in the brain. As always, talk with your doctor about ways to treat stress — particularly chronic stress — and depression. Though researchers continue to search for better treatments, there are many that have been shown to be very effective that exist right now.

The research is published in the journal Molecular Psychiatry.

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