Why does stress overwhelm some people while others come through it just fine? A very elegant new study came out this month in the high impact scientific journal, Cell, addressing this question. Researchers investigated some brain functions underlying why some people are highly susceptible to stress and others seem relatively resistant. Although the studies were done in mice, the potential application to humans, which I will discuss below, is not a stretch.



Stress can lead to depression . . . sometimes

The researchers used a basic model to stress mice by placing them in the same cage with a bully mouse for about 15 minutes a day, for ten days in a row. This experimental paradigm is accepted as a model for how humans experience social stress; for example interacting with a jerk for a boss at work, or at bully at school.

After exposure to this social stress, researchers tested the mice for other behaviors that indicate depression, anxiety or stress disorders. Yes, mice and rats can show these behaviors if you know how to look for them.

We cant give them a questionnaire to explore how the feel. But we can look at things like how willing they are to work for a reward (like sugar water) or how adventurous they are at exploring new environments or new social interactions. All of these are indicators of mood.

Whenever researchers do these types of studies there is always a variety of responses from the animals. Some will be susceptible to the bullying treatment and show signs of depression behavior and others will be resilient.

Sometimes its good to forget

The new studies looked at the underlying neurochemistry in a part of the brain called the VTA, which regulates mood, and found something very interesting. Mice that had lower activity of a specific brain hormone, called BDNF, in the mood regulating brain region were more resilient.

The paradox is that BDNF is important for learning and memory and mice that are low in BDNF activity typically have learning and memory problems. The new study suggests that under some conditions (i.e. stress) being a poor learner is an advantage because you wont get too hung up on the bad experience.

The mice in these experiments were, in a sense, predetermined to be susceptible or resilient to stress based on their learning skills. The point is that you have certain predispositions as to whether or not you will succumb to bad experiences and develop a stress disorder.

Can you blame it on your brain chemistry?

This seems a bit fatalistic to me, and I like to believe that humans have more control. We have a big cortex, which is the part of the brain that allows us to reason. We can choose how much value we put on an experience and alter the ability to learn.

Learning anything requires some degree of salience. The more important or the stronger we feel about an experience the better it will be burned into our memories. So how does this help?

With practice, we can control the intensity of our emotions in any given situation. We can, in a sense, choose if an experience will have a long-term effect. The stronger the experience, the more difficult it will be to exert control, but it is still there.

For example, participating in battle in war is an extremely strong experience and our ability to control our susceptibility to that will be limited. Whereas having someone call you a bad name should be much easier to get over and forget about.

Still, some people can come through war with few psychological problems while others may develop a stress disorder. On the other end of the spectrum, someone may be distraught for a lifetime over a getting their feelings hurt once.

You dont lack control

The point I am trying to make is that, with a practice of optimism you can tip the scales in favor of being resilient. You can, to some degree, use your cortex (reason) to remove the emotional strength of a bad experience and make it more difficult for that experience to take you down.

I make this point because the media jumped quickly on the conclusions from the new study that indicated a predetermined response to handling stress. I see a dangerous trend in many neuroscience studies trying to blame behavior on our brain chemistry. While this may be true in animals, I dont believe that people are that hard-wired and think we need to maintain a greater standard of personal responsibility.