PROVIDENCE, R.I. – Researchers at Brown University have identified increased activity in specific brain regions of individuals with obsessive-compulsive disorder (OCD) during complex cognitive tasks, a finding that could refine treatment strategies and diagnostic approaches. The study, published in Imaging Neuroscience, pinpointed differences in brain activity even when participants with OCD performed as well as those without the disorder.
The research, led by postdoctoral research associate Hannah Doyle and conducted in the laboratory of Associate Professor of Brain Science Theresa Desrochers at the Carney Institute for Brain Science, focused on “abstract sequential behavior” – the ability to follow a general order of steps even when individual actions vary, such as the routine of getting dressed. Researchers hypothesized a link between this type of sequencing and OCD, a condition characterized by intrusive thoughts and repetitive behaviors.
Participants in the study were asked to name the color or shape of objects in a specific sequence whereas undergoing magnetic resonance imaging (MRI). While both groups – those diagnosed with OCD and a control group – demonstrated similar performance on the task, the MRI scans revealed that individuals with OCD engaged a broader network of brain regions.
“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.
Specifically, the study identified increased activity in areas associated with motor and cognitive task control, working memory, and object recognition. Notably, some of these regions – including the middle temporal gyrus and an area spanning part of the occipital gyrus and the temporo-occipital junction – had not previously been strongly linked to OCD. The middle temporal gyrus is involved in working memory, semantic memory retrieval and language processing, while the latter region plays a role 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, suggested the findings could enhance the effectiveness of transcranial magnetic stimulation (TMS), a treatment approved by the U.S. Food and Drug Administration for OCD in 2018. Current TMS therapy shows improvement in roughly 30-40% of patients.
“If we reposition coils during TMS treatments to be near these brain regions, we might end up seeing a greater improvement in symptoms,” McLaughlin said.
Desrochers emphasized the importance of using a real-world-relevant task in the study. “A lot of tasks that are used in a clinical setting are static,” she explained. “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 required participants to alternate between categorizing by color and shape, demanding both sequential tracking and cognitive flexibility.
The research team is now exploring the potential of using the sequencing task as a diagnostic 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 assist indicate that TMS treatment may be effective for symptom reduction.”
The study was funded by the National Institute of Mental Health (R01MH131615) and the National Institute of General Medical Sciences (P20GM130452).
