Objective: Results from structural neuroimaging studies of obsessive-compulsive disorder (OCD) have been only partially consistent. The authors sought to assess regional gray and white matter volume differences between large samples of OCD patients and healthy comparison subjects and their relation with demographic and clinical variables.Method: A multicenter voxel-based morphometry mega-analysis was performed on 1.5-T structural T 1 -weighted MRI scans derived from the International OCD Brain Imaging Consortium. Regional gray and white matter brain volumes were compared between 412 adult OCD patients and 368 healthy subjects.

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Aim:This study attempted to determine whether Anorexia nervosa (AN), Bulimia nervosa (BN) and Obsessive Compulsive Disorder (OCD) share clinical and psychopathological traits.Methods:The sample consisted of 90 female patients (30 OCD; 30 AN; 30 BN), who had been consecutively referred to our Unit. All subjects met DSM-IV criteria for those pathologies. The assessment consisted on the Maudsley Obsessive-Compulsive Inventory, Questionnaire of obsessive traits and personality by Vallejo, Eating Attitudes Test-40, Eating Disorder Inventory, and Beck Depression Inventory. ANCOVA tests (adjusted for age and body mass index) and multiple linear regression models based on obsessive-compulsiveness, obsessive personality traits and perfectionism, as independent variables, were applied to determine the best predictors of eating disorder severity.Results:ANCOVA revealed several significant differences between obsessive-compulsive and eating disordered patients (MOCI, p < 0.001; EAT, p < 0.001; EDI, p < 0.001), whereas some obsessive personality traits were not eating disorder-specific. 16.7% OCD presented a comorbid eating disorder, whereas 3.3% eating disorders had an OCD diagnosis. In the eating disorder group, the presence of OC symptomatology was positively associated (r = 0.57, p < 0.001) with the severity of the eating disorder. The results were maintained after adjusting for comorbidity.Conclusions:Although some obsessive-compulsive and eating disorder patients share common traits (e.g. some personality traits especially between OCD and AN), both disorders seem to be clinically and psychopathologically different.

Neurobiological models of obsessive-compulsive disorder (OCD) emphasize disturbances in the function and connectivity of brain corticostriatal networks, or "loops." Although neuroimaging studies of patients have supported this network model of OCD, very few have applied measurements that are sensitive to brain connectivity features. Objective: Using resting-state functional magnetic resonance imaging, we tested the hypothesis that OCD is associated with disturbances in the functional connectivity of primarily ventral corticostriatal regions, measured from coherent spontaneous fluctuations in the blood oxygenation level-dependent (BOLD) signal. Design: Case-control cross-sectional study. Setting: Hospital referral OCD unit and magnetic resonance imaging facility. Participants: A total of 21 patients with OCD (10 men, 11 women) and 21 healthy control subjects matched for age, sex, and estimated intelligence.

Current knowledge about functional connectivity in obsessive-compulsive disorder (OCD) is based on small-scale studies, limiting the generalizability of results. Moreover, the majority of studies have focused only on predefined regions or functional networks rather than connectivity throughout the entire brain. Here, we investigated differences in resting-state functional connectivity between OCD patients and healthy controls (HC) using mega-analysis of data from 1024 OCD patients and 1028 HC from 28 independent samples of the ENIGMA-OCD consortium. We assessed group differences in whole-brain functional connectivity at both the regional and network level, and investigated whether functional connectivity could serve as biomarker to identify patient status at the individual level using machine learning analysis. The mega-analyses revealed widespread abnormalities in functional connectivity in OCD, with global hypo-connectivity (Cohen’s d: -0.27 to -0.13) and few hyper-connections, mainly with the thalamus (Cohen’s d: 0.19 to 0.22). Most hypo-connections were located within the sensorimotor network and no fronto-striatal abnormalities were found. Overall, classification performances were poor, with area-under-the-receiver-operating-characteristic curve (AUC) scores ranging between 0.567 and 0.673, with better classification for medicated (AUC = 0.702) than unmedicated (AUC = 0.608) patients versus healthy controls. These findings provide partial support for existing pathophysiological models of OCD and highlight the important role of the sensorimotor network in OCD. However, resting-state connectivity does not so far provide an accurate biomarker for identifying patients at the individual level.