A brain study shows the roots of a TOC

They wash their hands several times in a row. They click on the switches again and again. They check – and double check, and check again – that they have turned off the stove.

Nobody knows exactly what drives people with obsessive-compulsive disorder to do what they do, even when they are fully aware of what they should not do and what they do. they hinder their ability to lead a normal life.

This lack of scientific understanding means that about half of them do not find an effective treatment.

But a new scan of brain scans of hundreds of people with OCD and people without OCD could be helpful. More voluminous than any previous study, it identifies areas of the brain and processes related to these repetitive behaviors.

In simple terms, the study suggests that the brains of patients with OCD get stuck in a loop of "falseness," that patients can not stop even if they know they should.

Errors and stop signals

Researchers at the University of Michigan have assembled the largest ever set of task-based brain function and other OCD-based data analyzes and combined them for a new meta-analysis published in Biological psychiatry.

"These results show that, in OCD, the brain responds too much to errors and too little to stop the signals, anomalies that the researchers had suspected to play a crucial role in OCD, but which had not been demonstrated. conclusively because of the small number of participants in the individual studies, "says Luke Norman, Ph.D., lead author of the new study and postdoctoral researcher in the MU Department of Psychiatry.

"By combining the data from ten studies and nearly 500 healthy patients and volunteers, we have seen how long-established brain circuits that are crucial for OCD are actually involved in the disease," he said. declared. "It shows the power to do this kind of research in a more collaborative way."

New targets for therapy

Norman works with Kate Fitzgerald, MD, a member of the UM Psychiatry faculty, and Stephan Taylor, MD, co-director of the Michigan Medicine Pediatric Anxiety Program, the UM University Medical Center. , and is leading a clinical trial currently looking for OCD adolescents and adults to test the ability of targeted therapy sessions to treat OCD symptoms.

"This analysis paves the way for therapeutic goals in treating OCD because it shows that error treatment and inhibitory control are two important processes that are altered in people with the disease," says Fitzgerald.

"We know that patients often have a glimpse of their behavior and can detect that they are doing something pointless," she added. "But these results show that the error signal probably does not reach the brain network that needs to be activated for them to stop doing it."

Reduce brain differences

In their article, the researchers focus on the cingulo-opercular network. It is a set of brain areas connected by motorways of nerve connections located in the center of the brain. It is normally used to monitor errors or the potential need to interrupt an action and to involve the decision-making areas in the front of the brain when it detects that something is "off."

The brain scan data used in the new document was collected when patients with OCD and healthy people were asked to perform certain tasks while lying in a powerful functional MRI scanner. In total, the new analysis included analyzes and data from 484 children and adults, medicated and non-medicated.

Norman led the data combination in a carefully controlled manner, which allowed for the inclusion of brain scan data from studies conducted as far as possible in the Netherlands, the United States and Australia. .

This is the first time that a large-scale analysis includes data on brain tests performed when participants with OCD had to respond to errors during a brain scan and when they were not able to do so. they had to stop taking action.

The combined data revealed a consistent trend: compared to healthy volunteers, people with OCD were much more active in areas of the brain involved in recognizing that they were making a mistake, but less in areas that might help stop.

Disconnected brakes

Researchers recognize that these differences do not in themselves constitute a complete story – and they can not say, from the available data, whether the differences in activity are the cause or the result of the onset of life. an OCD.

But they suggest that OCD patients may have an "ineffective" link between the brain system that links their ability to recognize errors and the system that governs their ability to act against these errors. This could lead their overreaction to mistakes to overwhelm their underpowered ability to tell themselves to stop.

"It's as if their foot was on the brake telling them to stop, but the brake was not attached to the part of the wheel that could actually stop them," Fitzgerald said. . "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 for about half of the patients, and with such discoveries we hope to make CBT more effective or to guide new treatments. "

Translate results into clinical care

While OCD was once considered an anxiety disorder and patients are often worried about their behavior, it is now considered a separate mental illness.

It is now thought that the anxiety felt by many OCD patients is a side effect of their condition, caused by the recognition that their repetitive behaviors are not necessary, but by the inability to control the willingness to do so. .

The U-M team will test techniques to control this impulse and prevent anxiety in its TCC clinical trial for OCD. The study is currently researching adolescents and adults under the age of 45 with OCD, as well as adolescents and healthy adults who do not have OCD. There are two brain scans performed in the fMRI research U-M and 12 weeks of free therapy between the first and last scan.

Fitzgerald notes that the recently approved FDA (repetitive transcranial magnetic stimulation) rTMS for treating OCD targets some of the circuits that the U-M team has been striving to identify.

The rTMS concentrates the magnetic fields on certain areas of the brain from outside the skull. "If we know how brain regions interact to trigger and stop the symptoms of OCD, we know where to target rTMS," she says.

For severe OCD cases, brain surgery techniques have been proposed as an option over the past decade and the new findings are consistent with their effects. In such cases, neurosurgeons disconnect certain areas of the brain from each other with tiny bursts of energy or cuts, or insert a permanent probe capable of stimulating activity in a given area.

The authors of the new article ask neurosurgeons to examine new findings regarding the role of brain areas involved in the cingulo-opercular network, both in inhibitory control and in the treatment of errors, when deciding where and how when to intervene.

The bottom line for patients

The researchers also advocate studies using genetic tests and repeated fMRI brain imaging of the same OCD patients over time, as part of a longitudinal study. This could help researchers clarify the problem of "eggs and hen", whether error handling and inhibitory control problems are at the heart of OCD, or whether they are effects symptoms of OCD

Meanwhile, Norman, Fitzgerald and Taylor hope that the new discoveries will have a positive impact on people who are currently suffering from OCD and parents of children with signs of the disease.

"We know that OCD is a brain disorder and we better understand the potential brain mechanisms that underlie the symptoms and drive patients to struggle to control their compulsive behaviors," Norman said.

Fitzgerald adds, "It's not a profoundly dark behavior problem – OCD is a medical problem, not anyone's fault." Brain imaging allows us to study it. in the same way that heart specialists study the ECGs of their patients – and we can use this information to improve care and the lives of people with OCD. "

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