Systematic Changes in Cerebral Glucose Metabolic Rate After Successful Behavior Modification Treatment of Obsessive-Compulsive Disorder

TLDR

The study examined whether improvement in OCD symptoms after 10 weeks of exposure and response prevention therapy is associated with changes in caudate nucleus glucose metabolism and whether pre‑treatment correlations among orbital cortex, caudate, and thalamus diminish with symptom relief. Nine OCD patients underwent PET scans before and after the 10‑week behavioral program, and the data were combined with nine subjects from a prior study for analysis. Responders exhibited significant bilateral reductions in caudate glucose metabolism, larger than in poor responders, and pre‑treatment correlations between orbital gyri and caudate/thalamus decreased after treatment, confirming a prefrontal cortico‑striato‑thalamic network’s role in OCD.

Abstract

<h3>Background:</h3> We sought to determine in a new patient sample whether symptomatic improvement in obsessivecompulsive disorder treated with behavior modification is accompanied by significant changes in glucose metabolic rates in the caudate nucleus, measured with positron emission tomography, as seen in a previous study. Second, by combining samples from this and the previous study, we also examined whether there were pathologic correlational relationships among brain activity in the orbital cortex, caudate nucleus, and thalamus that obtained before behavioral treatment of obsessivecompulsive disorder, but that decreased significantly with symptom improvement. <h3>Methods:</h3> Nine patients with obsessive-compulsive disorder were studied with positron emission tomography before and after 10 weeks of structured exposure and response prevention behavioral and cognitive treatment. Results were analyzed both alone and combined with those from nine similar subjects from the previous study. <h3>Results:</h3> Behavior therapy responders had significant (<i>P</i>&lt;.05) bilateral decreases in caudate glucose metabolic rates that were greater than those seen in poor responders to treatment. Before treatment, there were significant correlations of brain activity between the orbital gyri and the head of the caudate nucleus and the orbital gyri and the thalamus on the right. These correlations decreased significantly after effective treatment. <h3>Conclusions:</h3> These results replicate and extend previous findings of changes in caudate nucleus function with behavior therapy for obsessive-compulsive disorder. A prefrontal cortico-striato-thalamic brain system is implicated in mediation of symptoms of obsessivecompulsive disorder.