MRI scans show that people diagnosed with OCD who have undergone CBT have intensified connectivity between key brain networks.
Obsessive-compulsive disorder (OCD) is a condition marked by inescapable, intrusive thoughts that cause anxiety (hence "obsessive"), and repetitive, ritualistic behaviors aimed at reducing that feeling (hence "compulsive").
OCD can be a debilitating condition and can severely impair daily functioning. The National Institutes of Mental Health estimate that, in the United States, the yearly prevalence of OCD amounts to 1 percent of the total adult population. Around half of these cases are deemed "severe."
Researchers from the University of California, Los Angeles - who were led by Dr. Jamie Feusner - have conducted a study aiming to find out whether and how CBT might change levels of activity and network connectivity in the brains of people diagnosed with OCD.
They explain that although the efficacy of CBT in treating OCD has been previously explored, this is likely the first study to use functional MRI (fMRI) to monitor what actually happens in the brains of people with OCD after exposure to this kind of therapy.
The researchers' findings were recently published in the journal Translational Psychiatry.
Changes in key brain regions following CBT
The team specifically targeted the effects of exposure and response prevention (ERP)-based CBT, which entails exposure to triggering stimuli and encouraging the individual to wilfully resist responding to those stimuli in the way that they normally would.
For the study, 43 people with OCD and 24 people without it were recruited. The results for the two groups were later compared, at which point the 24 individuals without OCD were taken as the control group.
All the participants diagnosed with OCD received intensive ERP-based CBT on an individual basis in 90-minute sessions on 5 days per week, for a total of 4 weeks.
Participants from both groups underwent fMRI. Those diagnosed with OCD, who had received CBT, were scanned both before the treatment period and after the 4 weeks of treatment. Participants from the control group, who did not undergo CBT, also had fMRI scans after 4 weeks.
When the scans of participants with OCD were compared, the results from before exposure to CBT and after it were found to be largely contrasting.
The researchers noticed that the brains of people with OCD exhibited a significant increase in connectivity between eight different brain networks, including the cerebellum, the caudate nucleus and putamen, and the dorsolateral and ventrolateral prefrontal cortices.
The cerebellum is involved with processing information and determining voluntary movements, while the caudate nucleus and putamen are key in learning processes and controlling involuntary impulses.
The dorsolateral and ventrolateral prefrontal cortices are involved with planning action and movement, as well as regulating certain cognitive processes.
Dr. Feusner and team point out that an increased level of connectivity between these cerebral regions suggests that the brains of the people who underwent CBT were "learning" new non-compulsive behaviors and activating different thought patterns.
He suggests that these changes may be novel ways of coping with the cognitive and behavioral idiosyncrasies of OCD.
"The changes appeared to compensate for, rather than correct, underlying brain dysfunction. The findings open the door for future research, new treatment targets, and new approaches."
Dr. Jamie Feusner
First study author Dr. Teena Moody adds that being able to show that there are quantifiable positive changes in the brain following CBT may give people diagnosed with OCD more confidence in following suitable treatments.
"The results could give hope and encouragement to OCD patients," says Dr. Moody, "showing them that CBT results in measurable changes in the brain that correlate with reduced symptoms."