Brain activity during reward anticipation and receipt was compared between 18 OCD patients and 19 healthy control subjects, using a monetary incentive delay task and functional magnetic resonance imaging. Reward processing was compared between OCD patients with predominantly contamination fear and patients with predominantly high-risk assessment.
Obsessive-compulsive disorder patients showed attenuated reward anticipation activity in the nucleus accumbens compared with healthy control subjects. Reduced activity of the nucleus accumbens was more pronounced in OCD patients with contamination fear than in patients with high-risk assessment. Brain activity during reward receipt was similar between patients and control subjects. A hint toward more dysfunctional reward processing was found in treatment-resistant OCD patients who subsequently were successfully treated with deep brain stimulation of the nucleus accumbens.
Obsessive-compulsive disorder patients may be less able to make beneficial choices because of altered nucleus accumbens activation when anticipating rewards. This finding supports the conceptualization of OCD as a disorder of reward processing and behavioral addiction.