Researchers randomly assigned 87 patients with OCD ranging in age from 12 to 45 years to receive 12 weeks of either CBT or stress management therapy (SMT). Prior to treatment, participants received functional MRI scans while performing an incentive flanker task designed to assess brain activation to reward processing and cognitive control.
Participants randomized to CBT had a better treatment response when their pre-treatment MRI showed greater activation within the ventromedial prefrontal, orbitofrontal, lateral prefrontal and amygdala regions during reward processing and within the right temporal lobe and rostral anterior cingulate during cognitive control.
In contrast, participants randomized to SMT had better treatment response when their pre-treatment activation in similar brain regions was reduced.
"Pinpointing the specific brain networks that predict response to CBT is important because this information can help us understand brain functions that may be particularly called upon during the course of treatment," said study coauthor Luke Norman, a scientist at the National Human Genome Research Institute at the National Institutes of Health in Bethesda, Maryland.
"This type of precision medicine in psychiatry would allow doctors to select the best treatment for each patient based on individual characteristics their illness, such as patterns of brain function," Norman said by email.
Prior to the study, researchers had anticipated that more activation in brain networks involved in self-regulation and motivation would be associated with a better treatment response to CBT, Norman said. That's because the challenges of engaging directly in triggers of OCD symptoms and resisting acting on compulsive avoidance behaviors can mean people undergoing CBT require a great deal of self-motivation and continued motivation, Norman said.
The researchers were surprised, though, by the results in the control group of participants randomized to SMT.
"We speculate that, since the control therapy aimed at improving relaxation and problem-solving skills in the face of stressful challenges, it might work best for patients who are less able to engage brain networks underlying these skills," Norman said.
Results were similar for adolescents and adults in the study, suggesting that neural predictors of CBT outcomes may be consistent across the lifespan, the study team concludes in the American Journal of Psychiatry.
Although outcome assessments were blinded to whether participants received CBT or SMT, one limitation of the study is that it was not possible for patients to be blinded to treatment received, the authors note.
While it may not be practical to do an MRI for every OCD patient, the results do suggest that it may be possible to evaluate individual patients to identify the kinds of characteristics that might better predict who would respond best to a specific type of therapy, said study co-author Dr. Kate Fitzgerald, a pediatric OCD specialist at Michigan Medicine in Ann Arbor.
Easily administered behavioral tests could be developed to help therapists recommend CBT to those who have the most cognitive control and reward responsiveness, and SMT to those who would benefit most from being taught to relax and use problem-solving techniques to improve their response to stressors, Dr. Fitzgerald said in an emailed statement.
Computer-based brain-training exercises that can strengthen these tendencies, and rewards for exposing oneself to the thing or action that triggers OCD symptoms, could also potentially help improve treatment response, Dr. Fitzgerald said.
"This kind of research may help inform efforts to do cognitive control training and ramp up the circuits that help patients overcome conflict between obsessive fears and insight that these fears don't make sense so that patients can dismiss the fear as improbable, rather than trying to make it go away with compulsive behaviors," Dr. Fitzgerald said. "Our research shows that different brains respond to different treatments, and if we can build on this knowledge we could move toward a more precision-medicine approach for OCD."
By Lisa Rapaport
SOURCE: https://bit.ly/3n6r8Nu American Journal of Psychiatry, online August 28, 2020.
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