Abstract

Previous resting-state functional magnetic resonance imaging (rs-fMRI) studies of obsessive-compulsive disorder (OCD) have facilitated our understanding of OCD pathophysiology based on its intrinsic activity. However, whether the group difference derived from univariate analysis could be useful for informing the diagnosis of individual OCD patients remains unclear. We aimed to apply multivariate pattern analysis of different rs-fMRI parameters to distinguish drug-naive patients with OCD from healthy control subjects (HCS). Fifty-four drug-naive OCD patients and 54 well-matched HCS were recruited. Four different rs-fMRI parameter maps, including the amplitude of low-frequency fluctuations (ALFF), fractional amplitude of low-frequency fluctuations (fALFF), regional homogeneity (ReHo) and functional connectivity strength (FCS), were calculated. Training of a support vector machine (SVM) classifier using rs-fMRI maps produced voxelwise discrimination maps. Overall, the classification accuracies were acceptable for the four rs-fMRI parameters. Excellent performance was achieved when ALFF maps were employed (accuracy, 95.37%, p < 0.01), good performance was achieved by using ReHo maps, weaker performance was achieved by using fALFF maps, and fair performance was achieved by using FCS maps. The brain regions showing the greatest discriminative power included the prefrontal cortex, anterior cingulate cortex, precentral gyrus, and occipital lobes. The application of SVM to rs-fMRI features may provide potential power for OCD classification.

Highlights

  • Obsessive-compulsive disorder (OCD) is a common debilitating disorder characterized by persistent intrusive thoughts and repetitive actions, with a prevalence of 1% to 3%1

  • Group comparison by voxelwise univariate analysis Compared with the healthy control subjects (HCS), patients with OCD had significantly increased amplitude of low-frequency fluctuations (ALFF) values in the left ventral medial prefrontal cortex, right dorsal lateral prefrontal cortex and bilateral insula; OCD patients showed lower ALFF values in the right inferior parietal lobe (IPL), occipital lobe at a threshold of p < 0.05

  • The regions that contributed to the identification of patients with OCD (OCD > HCS) in the ALFF discrimination map included the left ventral medial prefrontal cortex (vmPFC), right dorsal lateral prefrontal cortex and bilateral insula

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Summary

Introduction

Obsessive-compulsive disorder (OCD) is a common debilitating disorder characterized by persistent intrusive thoughts and repetitive actions, with a prevalence of 1% to 3%1. Among various rs-fMRI parameters, both the amplitude of low-frequency fluctuations (ALFF) and the fractional ALFF (fALFF) of the BOLD signal measure. Regional homogeneity (ReHo) measures Kendall’s coefficient concordance in neighboring voxels to reflect the coherence of the BOLD signal amplitude between a single voxel and its nearest neighbors[8]. Given the computational basis of this parameter, it has been suggested as a measure of localized connectivity[9], providing information about local alterations in brain function. Unlike the functional connectivity approach, all of these parameters do not require a priori seed selection; they have the potential to evaluate abnormalities of certain brain regions at the whole-brain level

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