Why Stress Leads Us to Make Bad Decisions and Do Stupid Things

Stressful experiences may affect your brain, which in turn may make it harder for you to be rational. If you’ve ever found yourself making an impulsively risky decision, ask yourself, Were you stressed about anything at the time? Sodanle Chea on Flickr

If you've ever found yourself making an impulsively risky decision, ask yourself, Were you stressed about anything at the time? Maybe you got fired or got sick or had a conflict with your partner?

Well, that stressful experience may have affected your brain, which in turn may have made it harder for you to be rational, new research suggests.

Researchers at Massachusetts Institute of Technology (MIT) wanted to understand what can influence people (and mice) to make risky decisions. They obtained groups of mice and gave them two choices: In one option, they could go through a maze with reasonable lighting and diluted chocolate milk at the end. Alternatively, they could go through another maze that had harsh, annoying lights and concentrated chocolate milk at the end. The more concentrated the milk, the happier the mouse. However, in order to get to that concentrated chocolate milk, they had to make a sacrifice: going through an unpleasant maze, according to MIT News.

They took two groups of mice and subjected one group to daily stress. They let each set of mice choose which maze they preferred and found that the stressed mice were far more likely to choose the high-risk, high-reward maze. The effect lasted for months.

This study lends insights into how neurological disorders affect people. People who suffer from addiction, depression and post-traumatic stress disorder sometimes experience impulsiveness and difficulty making rational decisions. It could be the stress of dealing with inabilities to function properly and staving off cravings, compounded with the chemical effects on the brain, that are influencing people's uninhibited behavior.

Surprisingly, the researchers found that they could change the impulsive behavior in the mice by manipulating a particular circuit in prefrontal cortex of the brain. They first affected mice in ways that made them more impulsive, or more likely to choose the high-stakes chocolate milk scenario, even as the researchers made the low-risk chocolate milk slightly more chocolaty. But could they do the opposite and make the mice less impulsive? The scientists suggest that, if they could manipulate this circuit in humans with brain disorders, it could have therapeutic effects.

Striosomes are chemical compartments that are necessary for brain function. But abnormalities in striosomes can cause mood disorders. Cortical neurons inhibit striosome activity, but stress slows their firing, making them too late to inhibit risk-taking behavior.

So the next time you're stressed out, try not to make high-impact decisions until you've relaxed a bit. The chocolate milk might not be worth it.