A brain-scan study of people with obsessive-compulsive disorder (OCD) has shown that as little as four weeks of daily cognitive-behavioural therapy (CBT) can produce significant changes in activity in certain regions of the brain. Past brain-scan studies of people with OCD have demonstrated that elevated activity along the frontal-subcortical circuits of the brain decreases in response to treatment with serotonin reuptake inhibitors (SRIs) or CBT. However, clinical improvement of OCD symptoms was expected to require up to 12 weeks of behavioural therapy or medication. The therapy used in the trial was "exposure and response prevention" which gradually desensitizes people to things that provoke obsessional fears or worries. After four weeks of therapy the OCD patients showed significant improvements in OCD symptoms, depression, anxiety and overall functioning. The brain scans showed significant reductions in brain activity in the right and left thalamus after treatment and a significant increase in activity in an area of the brain called the right dorsal anterior cingulate cortex, a region involved in reappraisal and suppression of negative emotions.
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