Excessive Worriers Might Have Their Big Brains to Blame

Scientists have pinpointed where your hand-wringing originates.
May 18, 2017, 3:55pm

Everybody worries. But there's a clinical difference between heightened stress about the future—a mere personality trait that psychologists call "intolerance of uncertainty"—and a legitimate obsessive compulsive or anxiety disorder. Now scientists at Dartmouth College have identified a part of the brain that seems to be connected to excessive fear of the future in people without clinical diagnoses.

The researchers performed magnetic resonance imaging (MRI) scans of 61 people who did not have clinical anxiety or OCD. An analysis of the scans revealed that people who scored higher on a psychological measure of intolerance of uncertainty also had a greater volume of grey matter in the striatum, which sits deep in the center of your brain and plays a big role in planning and motivation. The results were released today in the journal Emotion.

Previous studies had shown that people with OCD and anxiety also tended to have a larger striatum, leading researchers to believe that the brain region might play an important role in those disorders. What's more, intolerance of uncertainty is a personality trait that often shows up for the ride with both those psychological disorders. It's an all-consuming fear of what might go wrong that's worse than things actually going wrong, like agonizing over how someone you met on Tinder might respond to your text, or if you might be suddenly fired when you show up to work.

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But since this study examined only the brains of people without a diagnosis, that means the bigger striatum in OCD and anxiety is linked to the personality trait itself. "Having a relatively enlarged volume of the striatum may be associated with how intolerant you are when facing an uncertain future, but it does not mean you have GAD [general anxiety disorder] or OCD," says study author Justin Kim, now a postdoctoral associate at Duke University.

There's no way to tell at this point exactly why the additional grey matter, which is composed of the neurons that make up your brain, impacts how much you worry about the future. But linking the striatum to uncertainty offers some clues to why most people feel anxious about the future. "Given that an important component of IU is a desire for predictability, our findings offer a neuroanatomical link related to our need for predictability," Kim says. "When we feel we know what will happen next, this decreases our baseline levels of anxiety, allowing us to focus and get our work done with less distraction."

Pinpointing this brain region also creates new avenues for diagnosis and treatment. A brain scan could even spot an enlarged striatum and tell you whether or not you're at risk for developing OCD or an anxiety disorder in the future. Once scientists unlock the neurochemistry of the striatum, they could potentially create medications that target brain activity there and help alleviate excessive worry. And even with current treatments, it might be possible to use MRI scans of the region to determine how the brain is responding to attempts to alleviate the symptoms.

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