Although hoarding disorder (HD) has been historically conceptualized as a subtype or dimension of obsessive-compulsive disorder (OCD), preliminary evidence suggests that these two disorders have distinct neural underpinnings. The aim of the present study was to compare the hemodynamic responses of HD patients, OCD patients, and healthy controls (HC) during response inhibition on a high-conflict Go/NoGo task that has previously proved sensitive to OCD. Participants comprised 24 HD patients, 24 OCD patients, and 24 HCs who completed a Go/NoGo task during functional magnetic resonance imaging (fMRI). Although behavioral data showed no difference among the groups in Go/NoGo task performance, significant differences in hemodynamic activity were noted. During correct rejects (successful response inhibition), HD patients showed greater right precentral gyrus activation, whereas OCD patients exhibited greater right orbitofrontal activation, as assessed using a region of interest approach. During errors of commission (response inhibition failures), OCD patients, but not HD patients, were characterized by excessive activity in left and right orbitofrontal gyrus. The present results lend further support to the biological distinction between HD and OCD, and they are consistent with previous research suggesting frontal hypoactivity in HD patients during hoarding-unrelated tasks.
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