Abstract
Recent developments in psychoradiological researches have highlighted the disrupted organization of large-scale functional brain networks in obsessive-compulsive disorder (OCD). However, whether abnormal activation of localized brain areas would affect network dysfunction remains to be fully characterized. We applied both univariate analysis and multivariate pattern analysis (MVPA) approaches to investigate the abnormalities of regional homogeneity (ReHo), an index to measure the localized connectivity, in 88 medication-free patients with OCD and 88 healthy control subjects (HCS). Resting-state functional magnetic resonance imaging (RS-fMRI) data of all the participants were acquired in a 3.0-T scanner. First, we adopted a traditional univariate analysis to explore ReHo alterations between the patient group and the control group. Subsequently, we utilized a support vector machine (SVM) to examine whether ReHo could be further used to differentiate patients with OCD from HCS at the individual level. Relative to HCS, OCD patients showed lower ReHo in the bilateral cerebellum and higher ReHo in the bilateral superior frontal gyri (SFG), right inferior parietal gyrus (IPG), and precuneus [P < 0.05, family-wise error (FWE) correction]. ReHo value in the left SFG positively correlated with Yale–Brown Obsessive Compulsive Scale (Y-BOCS) total score (r = 0 0.241, P = 0.024) and obsessive subscale (r = 0.224, P = 0.036). The SVM classification regarding ReHo yielded an accuracy of 78.98% (sensitivity = 78.41%, specificity = 79.55%) with P < 0.001 after permutation testing. The most discriminative regions contributing to the SVM classification were mainly located in the frontal, temporal, and parietal regions as well as in the cerebellum while the right orbital frontal cortex was identified with the highest discriminative power. Our findings not only suggested that the localized activation disequilibrium between the prefrontal cortex (PFC) and the cerebellum appeared to be associated with the pathophysiology of OCD but also indicated the translational role of the localized connectivity as a potential discriminative pattern to detect OCD at the individual level.
Highlights
Obsessive-compulsive disorder (OCD) is among the most debilitating mental illnesses that influence nearly 2.3% of the general population (Abramowitz et al, 2009)
The current study applied both univariate analysis and multivariate pattern analysis (MVPA) approach to explore the alterations of regional homogeneity (ReHo) in a relatively large cohort of medication-free patients with OCD
Our study revealed that OCD patients showed lower ReHo in the bilateral cerebellum and higher ReHo in the frontoparietal regions compared with healthy control subjects (HCS)
Summary
Obsessive-compulsive disorder (OCD) is among the most debilitating mental illnesses that influence nearly 2.3% of the general population (Abramowitz et al, 2009). Previous review of voxel-based morphometry studies reported gray matter alterations of both ‘‘affective’’ and ‘‘executive’’ circuits in OCD patients (Piras et al, 2015). For functional MRI (fMRI) researches in OCD, patients show abnormal activation in several brain regions, which are essential for some domains of neuropsychological function such as decision making [ventromedial orbitofrontal cortex (OFC)] (Norman et al, 2018), error monitoring [amygdala, presupplementary motor area (preSMA), and subgenual anterior cingulate cortex] (Grützmann et al, 2016), response inhibition [inferior parietal gyrus (IPG), inferior frontal gyrus, and preSMA] (de Wit et al, 2012), reward-based learning (hippocampus, putamen, and amygdala; Marsh et al, 2015), fear conditioning (caudate and hippocampus) and extinction recall (cerebellum, posterior cingulate cortex, and putamen; Milad et al, 2013), cognitive flexibility [caudate and ventrolateral prefrontal cortex (PFC)], as well as goal-directed planning (putamen and dorsolateral PFC; Vaghi et al, 2017). Findings from task-based neuroimaging studies varied remarkably as different paradigms or analytic methods were adopted
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