Study reveals insights about brain regions linked to OCD, informing potential treatments

(Press-News.org) PROVIDENCE, R.I. [Brown University] — A new study revealed that certain brain regions are more active in people with obsessive-compulsive disorder (OCD) during cognitively demanding tasks. The findings could help inform new ways in which the condition is treated and assessed.

The study, published in Imaging Neuroscience, was conducted by researchers in the laboratory of Theresa Desrochers, an associate professor of brain science and of psychiatry and human behavior at Brown University’s Carney Institute for Brain Science.

Desrochers studies abstract sequential behavior, which is behavior — such as getting dressed in the morning — that follows a general sequence even though individual steps may vary. For the study, the team examined potential links between abstract sequencing and OCD, a prevalent psychiatric disorder characterized by repetitive thoughts and associated compulsive actions that cause distress for the diagnosed person.

“We started looking into OCD because symptoms of the condition suggest that patients lose track or get stuck where they are while performing sequences,” said lead study author Hannah Doyle a postdoctoral research associate in Desrochers’ lab.

For the study, researchers asked participants to perform a sequential cognitive task while in a magnetic resonance imaging (MRI) scanner, naming the color or shape of an object in a specific order. Doyle found that while individuals with OCD were able to perform the sequence as well as the control group (people who were not diagnosed with OCD), the MRI scans revealed differences in brain regions connected to motor and cognitive task control, working memory and object recognition.

“Their behavior looked similar, but the brains of the participants with OCD recruited more brain regions than the people in the control group,” Doyle said.

She noted that some of the regions hadn’t previously been linked to OCD. Those regions include the middle temporal gyrus — involved in working memory, semantic memory retrieval and language processing — and an area spanning part of the occipital gyrus and the temporo-occipital junction, which is involved in lower-level visual stimulus processing and object recognition.

Study co-author Nicole McLaughlin, an associate professor of psychiatry and human behavior at Brown and a neuropsychologist at Butler Hospital, said the findings may lead to new treatment targets for OCD, especially when involving transcranial magnetic stimulation (TMS). TMS is a therapy that uses magnetic pulses to stimulate brain regions implicated in a psychiatric disorder. The procedure was approved as a treatment for OCD by the U.S. Food and Drug Administration in 2018; research has shown TMS leads to improvement in about 30-40% of OCD patients.

According to McLaughlin, the treatment might be even more effective if the newly implicated regions are targeted: “If we reposition coils during TMS treatments to be near these brain regions, we might end up seeing a greater improvement in symptoms,” she said.

The real-life relevance of the cognitive task used in the study was key to the team’s insights.

“A lot of tasks that are used in a clinical setting are static,” said Desrochers. “But as humans, we interact with the world through sequences, where we organize information and make decisions. So we're asking people to do a task where these different control systems have to interact.”

The sequencing task calls for participants to name the colors or shapes of a series of images in a particular order, such as color, color, shape, shape, requiring the ability to keep track of a sequence while making a categorization decision.

“This task gets us closer to understanding what actually looks different in the brain for folks with OCD when all of these different cognitive control systems are trying to work together,” Desrochers said.

The researchers are testing the possibility of using the sequence task itself as an assessment tool.

“We are planning to use the task between treatments,” McLaughlin said. “If we start to see OCD patients’ brains looking more like control participants when they perform the task, that could help indicate that TMS treatment may be effective for symptom reduction.”

The research was funded by the National Institute of Mental Health (R01MH131615) and the National Institute of General Medical Sciences (P20GM130452). 

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