Brain activation in paediatric obsessive compulsive disorder during tasks of inhibitory control.

Background: Obsessive-compulsive disorder (OCD) may be related to a dysfunction in frontostriatal pathways mediating inhibitory control. However, no functional magnetic resonance imaging (fMRI) study has tested this in children.

Aims: To test whether adolescents with OCD in partial remission would show abnormal frontostriatal brain activation during tasks of inhibition.

Method: Event-related fMRI was used to compare brain activation in 10 adolescent boys with OCD with that of 9 matched controls during three different tasks of inhibitory control.

Results: During a 'stop' task, participants with OCD showed reduced activation in right orbitofrontal cortex, thalamus and basal ganglia; inhibition failure elicited mesial frontal underactivation. Task switching and interference inhibition were associated with attenuated activation in frontal, temporoparietal and cerebellar regions.

Conclusions: These preliminary findings support the hypothesis that paediatric OCD is characterised by a dysregulation of frontostriatothalamic brain regions necessary for motor inhibition, and also demonstrate dysfunction of temporoparietal and frontocerebellar attention networks during more cognitive forms of inhibition.