Brain Imaging Shows Overactive Habit System in OCD

A new study has found that misfiring of the brain’s habit control system may be behind the compulsions in obsessive-compulsive disorder (OCD).

The study, led by Dr. Claire Gillan and Professor Trevor Robbins of the Department of Psychology at the University of Cambridge, is the latest in a series of studies from the Cambridge Behavioural and Clinical Neuroscience Institute investigating the possibility that compulsions in OCD are products of an overactive habit system.

This research has shifted opinion away from thinking of OCD as a disorder caused by worrying about obsessions or faulty beliefs, towards viewing it as a condition brought about when the brain’s habit system runs amok, according to the Cambridge researchers.

In a study funded by the Wellcome Trust, the researchers scanned the brains of 37 people with OCD and 33 healthy people while they repetitively performed a simple pedal-pressing behavioral response to avoid a mild electric shock to the wrist.

The researchers found that the patients with OCD were less capable of stopping these pedal-pressing habits. This was linked to excessive brain activity in the caudate nucleus, a region that must fire correctly in order for us to control our habits, the researchers explained.

Basic imaging work has long since established that the caudate is overactive when the symptoms of OCD are provoked in patients, the researchers noted. That the habits the researchers trained in these patients in the laboratory also triggered the caudate to over-fire adds weight to the theory that compulsions in OCD may be caused by the brain’s habit system, they noted.

The researchers added that the findings are not specific to OCD and that, in fact, habits may be behind many aspects of psychiatry.

“It’s not just OCD — there are a range of human behaviors that are now considered examples of compulsivity, including drug and alcohol abuse and binge-eating,” said Gillan, who is now at New York University.

“What all these behaviors have in common is the loss of top-down control, perhaps due to miscommunication between regions that control our habits and those such as the prefrontal cortex that normally help control volitional behavior. As compulsive behaviors become more ingrained over time, our intentions play less and less of a role in what we actually do.”

The researchers said they think this is the work of our habit system.

“While some habits can make our life easier, like automating the act of preparing your morning coffee, others go too far and can take control of our lives in a much more insidious way, shaping our preferences, beliefs and, in the case of OCD, even our fears,” said Robbins.

“Such conditions, where maladaptive, repetitive habits dominate our behavior, are among the most difficult to treat, whether by cognitive behavior therapy or by drugs.”

The study emphasizes the importance of treating OCD early before the dysfunctional behavior becomes entrenched and difficult to treat, added Professor Barbara Sahakian, a co-author of the study.

The study was published in the American Journal of Psychiatry.

Source: University of Cambridge

Abstract of brain photo by shutterstock.