Neural correlates of symptom reduction after CBT in obsessive-compulsive washers—An fMRI symptom provocation study

• We examined neurofunctional changes associated with symptom reduction in OCD washers.
• Methods applied: fMRI, CBT, individualized and standardized symptom provocation.
• OCD patients showed reduced activity in key regions of the fronto-striatal network.

There is little knowledge about the neurofunctional changes associated with symptom reduction in obsessive-compulsive disorder (OCD). This functional Magnetic Resonance Imaging (fMRI) study explores changes in responses towards symptom provocation after psychotherapy.Twelve patients with washing compulsions and twelve case-by-case matched healthy controls participated in a symptom provocation fMRI experiment. All participants were confronted with pictures of standardized and individualized OCD triggers. The experiment was performed before and after an individual ambulatory cognitive-behavioral therapy (CBT).Post-treatment, OCD patients compared to healthy controls displayed reduced activity in key regions of the fronto-striatal network. While individualized symptom provocation demonstrated reductions in nucleus accumbens and posterior supramarginal gyrus, standardized symptom provocation showed reductions in orbitofrontal cortex, nucleus caudatus, ventrolateral prefrontal cortex, and anterior supramarginal gyrus. OCD patients showed significantly reduced symptoms after treatment, with a large effect size.These post-treatment reductions are discussed in the light of the current research on OCD, CBT, and the functional roles of the respective brain regions. The present study provides evidence for changes in the processing of disorder-relevant material, reflecting different aspects of psychotherapy-induced normalizations of neurofunctional dysregulations associated with OCD.