Background: Structural and functional fronto-striatal abnormalities are involved in the pathophysiology of obsessive-compulsive disorder (OCD). The aims of the present study were: (a) to investigate possible regional brain dysfunction in premotor cortico-striatal activity in drug-naïve children and adolescents with OCD; (b) to correlate brain activation with severity of obsessive-compulsive symptomatology; and (c) to detect possible changes in brain activity after pharmacological treatment.
Method: Twelve children and adolescents (age range 7-18 years; seven male, five female) with DSM-IV obsessive-compulsive disorder and twelve healthy subjects matched for age, sex and intellectual level were studied. Functional magnetic resonance imaging data were obtained during the performance of simple and complex sequences.
Results: Comparing the complex motor condition with the simple control condition, both patients and controls showed a pattern of cerebral activation involving the fronto-parietal cortex and basal ganglia. Compared with controls, OCD patients presented significantly higher brain activation bilaterally in the middle frontal gyrus. After 6 months of pharmacological treatment and with clear clinical improvement, activation in the left insula and left putamen decreased significantly.
Conclusion: In a paediatric OCD sample that was treatment naïve and without another psychiatric disorder we showed hyperactivation of the circuits that mediate symptomatic expression of OCD. The cerebral activation decreases after treatment and clinical improvement.