Background: Obsessive-compulsive disorder (OCD) is a psychiatric disorder which is characterized by recurrent intrusive thoughts (obsessions) and ritualized, repetitive behaviors or mental acts (compulsions). The gold standard for the treatment of OCD is cognitive behavioral therapy (CBT) with exposure and response prevention. This is the first study exploring the predictive value of resting-state functional connectivity for the outcome of CBT.
Methods: We assessed whole-brain resting-state functional connectivity in a group of 17 un-medicated OCD inpatients prior to CBT compared to 19 healthy controls using functional magnetic resonance imaging. The graph theoretical metric degree centrality served as indicator for altered voxel-wise whole-brain functional connectivity. The relative change in the Yale-Brown Obsessive Compulsive Scale (YBOCS) score was used to evaluate treatment outcome.
Results: The degree centrality of the right basolateral nuclei group of the amygdala was positively correlated with the response to subsequent CBT. OCD patients showed a lower degree centrality of the superficial amygdala (bilateral).
Conclusions: Our results suggest that two different sub-regions of the amygdala and their respective neural networks are affected in OCD: the superficial amygdala and networks related to evaluation of reinforcers and risk anticipation and the basolateral amygdala which is implicated in fear processing. The diminished CBT response in patients showing a lower degree centrality of the basolateral amygdala reflects a deficient fear circuit in these patients which may impact fear extinction as a core mechanism of exposure-based CBT.
Keywords: Amygdala; Degree centrality; Functional MRI; Functional connectivity; Graph theory; Obsessive compulsive disorder; Resting-state.
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