magnetic resonance spectroscopy of brain circuits in patients with first-episode obsessive-compulsive disorder

Background: obsessive-compulsive disorder (ocd) is considered neurodevelopmental disorder that shares the feature of dysfunctional frontal-subcortical circuitry, yet the relationship between structural abnormalities or neurobiochemistrical changes and ocd pathogenesis is still unknown. objectives: this study aims to use magnetic resonance spectroscopy (mrs) to discover substance-metabolism abnormalities of brain circuits in patients with first-episode ocd, and to study the mechanism of ocd. patients and methods: twenty patients with first-episode ocd and twenty gender- and age-matched normal controls were studied. neurochemical abnormalities, including ratios of n-acetylaspartate (naa), creatine (cr), and choline (cho), were measured in the prefrontal cortex, anterior cingulate cortex, orbitofrontal cortex, caudate nucleus, and thalamus with three-dimensional 1h-proton mrs (3d 1h-mrs). the data of the ratios in the two groups were analyzed with a independent samples t-test. results: cho/cr ratios in the thalamus were significantly higher in the first-episode ocd patients than in the controls (p < 0.01), and the naa/cr ratios in the caudate nucleus and thalamus were significantly lower in the first-episode ocd patients than in the controls (p < 0.01). however, naa/cr ratios in the anterior cingulate cortex and orbitofrontal cortex were higher in the first-episode ocd patients than in the controls (p < 0.01). conclusion: distinct neurochemical and histological structure changes (cortico-striatal-thalamic-cortical cycle) exist in patients with first-episode ocd. 1h-mrs is capable of identifying these changes by assessing metabolic abnormalities.