A functional magnetic resonance imaging study of inhibitory control in obsessive-compulsive disorder.

People with obsessive-compulsive disorder (OCD) have abnormalities in cognitive and motor inhibition, and it has been proposed that these are related to dysfunction of fronto-striatal circuits. However, nobody has investigated neuro-functional abnormalities during a range of inhibition tasks in adults with OCD. The aims of the study were to compare brain activation of people with OCD and controls during three tasks of inhibitory control. Ten unmedicated adults with OCD and 11 healthy controls performed three different tasks of motor and cognitive inhibitory control during event-related functional magnetic resonance imaging: a Go/No-go task (motor inhibition), a motor Stroop task (interference inhibition) and a Switch task (cognitive flexibility). People with OCD displayed significantly different patterns of brain activation compared to controls during all three tasks. During the Go/No-go and Switch experiments, people with OCD had underactivation in task-relevant orbitofrontal/dorsolateral prefrontal, striatal and thalamic regions. During the motor Stroop and Switch tasks, people with OCD also displayed underactivation in temporo-parietal areas. In the Go/No-go and motor Stroop tasks the OCD group showed increased activation compared to controls in cerebellum and predominantly posterior brain regions. OCD is associated with task-relevant fronto-striatal dysfunction during motor inhibition and cognitive switching. In addition, parieto-temporal dysfunction was observed during tasks with a higher attentional load.