Posted with permission from Popular Science

We're learning more about how compulsions work.

Symptoms of OCD are caused by problems in the brain.
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If you’re pretty sure that it’s going to be cold in the office, you’re likely to throw a sweater in your bag to ward off the chill. It makes sense that those two ideas would be related: if you’re confident about something, it’s natural for your actions to be consistent with what you know.

But for people with obsessive compulsive disorder, that natural relationship isn’t so natural. For them, there's a disconnect between their understanding of a likely outcome and their eventual action, according to a study published last week in the journal Neuron.

About two percent of adults in the U.S. have obsessive compulsive disorder (OCD), a mental illness characterized by the inability to control certain actions. Some people experience the stereotypical manifestations of the disorder—cleaning, counting—but it can also include obsession with a particular thought or idea, or rearranging items in a particular order.

Matilde Vaghi and Fabrice Luyckx, graduate students at the University of Cambridge and the University of Oxford, respectively, used a pong-like video game to get a better sense of the cognitive processes that go wrong in OCD. Participants moved a bucket around the outside of a circle with the goal of intercepting a ball, which would release from the center of the ring and land in the same spot each time. After each round they got a chance to adjust the bucket's position and try again. Before the ball left the center, they cited their level of confidence that the basket was actually in the correct position.

People without OCD used the information gathered from the different trials to move the bucket, and were able to use the patterns they saw in order to make their predictions. Both groups made moved the bucket more in response to a big miss from the preceding trial, but the group with OCD consistently made larger changes, even when the errors that they made were small.

The control group and the group with OCD had the same confidence in each of their decisions, which shows that both were recognizing the patterns of the ball's movement. What was different about the people with OCD was that they didn’t use that information when they moved the bucket between each trial. What’s more, patients with more severe symptoms of OCD had a larger disconnect between their confidence and their eventual action.

The study shores up a key aspect of the experiences of people with OCD: they know that they don’t need to wash their hands again and again, for example, but that they have no control over the action. That result wasn’t unexpected, Vaghi says, but it was still interesting to see a clear line from symptoms to the results from an abstract task like the one in the study. “It supported the way OCD patients manifest their systems,” she says.

The research also helps understand the overall relationship between confidence and action. Though the two often appear tightly coupled, Vaghi says, the results of this study show that they can be dissociated. “Having them coupled may be critical for better function,” she says. “If the two mismatch, there’s a problem.”

Christopher Pittenger, director of the OCD research clinic at Yale University says the disconnect between confidence and action is an interesting finding. “It’s conceptually very interesting, and people haven’t done a lot to tease the two apart,” he says. “The direction is very good...I hope the field will pay attention to it.”

The research group that Vaghi is a member of, Pittenger says, has been on the leading edge of computational modeling for disorders like OCD. That approach to research on behavior has been on the rise in the past five or so years, he says.

The drawback to this type of computerized methodology, he says, is that it can be more difficult to generalize the findings to the real world. “In order to make things trackable, you make them simple,” Pittenger says. So to know for sure that the effect shown in the study is real, it should be repeated with different types of tasks.

Vaghi and her collaborators are planning to look at the brain activity of people with OCD during the ball and basket task, in an attempt to pinpoint the regions of the brain involved in this particular dysfunctional activity. “Our hypothesis that the frontal striatal lobes are involved,” she says.

Vaghi’s overall goal is to help reduce stigma around mental illness, by identifying the physical roots of psychological problems. “I’d like everyone to know if you have mental illness it’s because you have a problem with your brain.”