Proton magnetic resonance spectroscopy in obsessive–compulsive disorder: Evidence for reduced neuronal integrity in the anterior cingulate

• We found a lower anterior cingulate NAA/Cr ratio in the OCD group than in controls.
• Low NAA/Cr ratio revealed a nearly significant trend for caudate and putamen.
• NAA/Cr ratios in the anterior cingulate were negatively correlated with Y-BOCS.
• Results underline the importance of anterior cingulate in pathophysiology of OCD.

Neuroimaging studies have suggested that dysfunction of the cortico-striatal-thalamo-cortical (CSTC) circuit is a key pathophysiologic feature of obsessive–compulsive disorder (OCD). Several studies using proton magnetic resonance spectroscopy (1H MRS) have found abnormal neural metabolite concentrations among OCD patients. The aim of this study was to investigate the metabolic integrity of the anterior cingulate, caudate and putamen in OCD. In the present study, 32 unmedicated patients with OCD, including 23 who were drug-naïve, were compared using MRS with 32 healthy controls. Metabolite levels of N-acetylaspartate (NAA), choline (Cho) and myo-inositol (mI) were measured in terms of their ratios to creatine (Cr). The ratio of NAA/Cr was significantly lower in OCD patients than in healthy controls in the anterior cingulate. There was a tendency for levels of NAA/Cr to be lower in the caudate and the putamen in patients with OCD compared with healthy controls. NAA/Cr ratios were negatively correlated with the total scores on the Yale–Brown Obsessive–Compulsive Scale (Y-BOCS) in the anterior cingulate in patients with OCD. Our results support the significance and biochemical involvement of the anterior cingulate cortex (ACC) in the pathophysiology of OCD.