In the largest brain scan analysis of its kind, researchers from the University of Michigan (U-M) have identified the specific brain regions and processes linked to the repetitive behaviors found in people with obsessive compulsive disorder (OCD).
The findings, published in the journal Biological Psychiatry, suggest that the brains of those with OCD get stuck in a loop of “wrongness,” even when patients know that what they’re doing doesn’t make sense.
“These results show that, in OCD, the brain responds too much to errors, and too little to stop signals, abnormalities that researchers had suspected to play a crucial role in OCD, but that had not been conclusively shown due to small numbers of participants in the individual studies,” says Dr. Luke Norman, lead author of the new study and a postdoctoral research fellow in the U-M Department of Psychiatry.
“By combining data from ten studies, and nearly 500 patients and healthy volunteers, we could see how brain circuits long hypothesized to be crucial to OCD are indeed involved in the disorder,” he says. “This shows the power of doing this kind of research more collaboratively.”
Norman works with U-M psychiatry faculty members Dr. Kate Fitzgerald and Dr. Stephan Taylor. Fitzgerald co-directs the Pediatric Anxiety Program at Michigan Medicine, U-M’s academic medical center and leads a clinical trial that is currently seeking teens and adults with OCD to test the ability of targeted therapy sessions to treat OCD symptoms.
“This analysis sets the stage for therapy targets in OCD, because it shows that error processing and inhibitory control are both important processes that are altered in people with the condition,” says Fitzgerald.
“We know that patients often have insight into their behaviors and can detect that they’re doing something that doesn’t need to be done,” she adds. “But these results show that the error signal probably isn’t reaching the brain network that needs to be engaged in order for them to stop doing it.”
The researchers focused on the cingulo-opercular network — a collection of brain areas linked by highways of nerve connections deep in the center of the brain. This brain network typically acts as a monitor for errors or the potential need to stop an action, and gets the decision-making areas at the front of the brain involved when it senses something is “off.”
The pooled brain scan data was collected when OCD patients and non-OCD individuals were asked to perform certain tasks while lying in a powerful functional MRI scanner. In all, the new analysis included scans and data from 484 children and adults, both medicated and not.
It’s the first time a large-scale analysis has included data about brain scans performed when participants with OCD had to respond to errors during a brain scan, and when they had to stop themselves from taking an action.
A consistent pattern emerged from the data: Compared with healthy participants, individuals with OCD had far more activity in the specific brain areas involved in recognizing that they were making an error, but less activity in the regions that could help them stop.
The team recognizes that these differences alone aren’t the full story, and they can’t tell from the available data if the differences in activity are the cause, or the result, of having OCD.
But they suggest that people with OCD may have an “inefficient” link between the brain system that connects their ability to recognize errors with the system that governs their ability to do something about those errors. This could push their over-reaction to errors to overwhelm their under-powered ability to tell themselves to stop.
“It’s like their foot is on the brake telling them to stop, but the brake isn’t attached to the part of the wheel that can actually stop them,” Fitzgerald says.
“In cognitive behavioral therapy sessions for OCD, we work to help patients identify, confront and resist their compulsions, to increase communication between the ‘brake’ and the wheels, until the wheels actually stop. But it only works in about half of patients. Through findings like these, we hope we can make CBT more effective or guide new treatments.”
While OCD was once classified as an anxiety disorder — and patients are often anxious about their behavior — it’s now seen as a separate mental illness.
The anxiety that many OCD patients experience is now believed to be a secondary effect of their condition, brought on by recognizing that their repetitive behaviors are not needed but being unable to control the drive to do them.
The research team hopes that people who currently have OCD, and parents of children with signs of the condition, will take heart from the new findings.
“This is not some deep dark problem of behavior — OCD is a medical problem, and not anyone’s fault. With brain imaging we can study it just like heart specialists study EKGs of their patients — and we can use that information to improve care and the lives of people with OCD,” says Fitzgerald.