[New advances in neuroimaging in the diagnosis of obsessive-compulsive disorder]

Brain-imaging research provides evidence to suggest that the underlying disfunction in Obsessive-Compulsive Disorder (OCD) is likely to be in the prefrontal cortex-basal ganglia thalamic circuit rather then in any one single brain region. Early computerized tomography and magnetic resonance imaging studies have shown morphological changes in the basal ganglia. Now more sophisticated techniques are enhancing the information available, specially with regard to the caudate nucleus. The serotonergic hypothesis remains a necessary but not sufficient explanation for the pathogenesis of OCD. Most evidence remains focussed on the basal ganglia and on a 5-HT/dopamine inter-relationship. Given the basal ganglia receive such rich innervation from both 5-Th and dopamine neurones, it has been postulated that OCD is subserved by a neuronal dysfunction in the basal ganglia and orbitofrontal cortex circuit. Combining behavioural challenge with brain imaging may be a better approach to capturing brain function while patients with OCD and control subjects are actually observed. Using this techniques has made it possible to identified changes in response to treatment, whether the treatment is pharmacological or behavioural. However, there are not data enough that allow us to understand the anatomical, physiological and chemical mechanisms implicated in OCD.