The new study, published in the American Journal of Psychiatry, examines advanced brain scans of 87 teens and adults with moderate to severe OCD who were randomly assigned 12 weeks of one of the two types of therapy.
The researchers found that in general, both types of therapy reduced the symptoms that participants experienced. The approach known as ‘exposure therapy’, a form of cognitive behavioral therapy, or CBT, was more effective and reduced symptoms more as time went on, compared with stress-management therapy, also known as SMT.
But when the researchers looked back at the brain scans taken before the patients began therapy, and linked them to individual treatment response, they found striking patterns.
The brain scans were taken while patients performed a simple cognitive task and responded to a small monetary reward if they did the task correctly.
Those who started out with more activation in brain circuits for processing cognitive demands and reward during the tests were more likely to respond to CBT – but those who started out with less activation in those same areas during the same tests were more likely to respond well to SMT.
“We found that the more OCD-specific form of therapy, the one based on exposure to the focus of obsession and compulsion, was better for relieving symptoms, which in itself is a valuable finding from this head-to-head randomized comparison of two treatment options,” says Stephan Taylor, M.D., the study’s senior author and a professor of psychiatry at Michigan Medicine, U-M’s academic medical center. “But when we looked at the brain to see what was behind that response, we found that the more strength patients had in certain brain areas were linked to a greater chance of responding to exposure-based CBT.”
The brain regions and circuits that had the strongest links to treatment have already been identified as important to OCD – and have even been targets for treatment with an emerging therapy called transcranial magnetic stimulation.
Specifically, stronger activity in the circuit called the cinguloopercular network during the cognitive task, and stronger activity in the orbitostriato-thalamic network when the reward was at stake, was associated with better response to exposure-based CBT. But lower activity in both regions was associated with better response to the stress-reduction SMT. The effects didn’t vary across age groups.
“These findings speak to a mechanism for therapy’s effects, because the brain regions associated with those effects overlap substantially with those implicated previously in this disorder,” says Luke Norman, Ph.D., who led the work as a U-M neuroscience postdoctoral fellow and is now a scientist at the National Institutes of Health. “This suggests we need to draw upon the most-affected networks during therapy itself, but further research is needed to confirm.”
The brain scans were done while patients underwent a test that required them to correctly pick the correct letter out of a display, and offered a potential monetary reward if they performed the task correctly. This measured both their ability to exert control over their cognitive processes in picking out the right letter, and the extent to which the promise of a reward motivated them.
One of the areas most linked to CBT treatment response was the rostral anterior cingulate cortex (rACC). Past research has already linked it to OCD and treatment response in general, and it’s thought to play a key role in self-regulation of response to OCD triggers. Previously, the U-M team had shown that in general, people with OCD tend to have reduced activation in the rACC when asked to perform tasks that involve cognitive control.
Among those who responded best to CBT, the researchers saw stronger pre-treatment activation in areas of the brain associated with learning how to extinguish fear-based responses to something that has caused fear in the past. Because exposure therapy for OCD involves facing the thing or situation that provokes obsessive and fearful responses, having a stronger ability to be motivated by rewards might help someone stick with therapy despite having to face their triggers.
The findings suggest a path to personalizing the choice of therapy not by doing brain scans on everyone with OCD – which would be impractical – but by using everyday tests that measure the kinds of characteristics that might predict better success with one therapy or the other.
Category(s):Obsessions & Compulsions (OCD)
Source material from University of Michigan
