Reduced Interhemispheric Resting-State Functional Homotopy in Obsessive-Compulsive Disorder

Abstract

Neuroimaging studies have shown structural and functional abnormalities in parts of the cortico-striato-thalamo-cortical (CSTC) brain circuitry in patients with obsessive-compulsive disorder (OCD). However, little is known about changes in the interhemispheric functional homotopy in the resting-state in OCD. This study used a voxel-mirrored homotopic connectivity (VMHC) approach combined with resting-state functional magnetic resonance imaging to investigate changes in interhemispheric functional homotopy in 60 OCD patients and 60 healthy controls. Compared with the healthy controls, the OCD patients showed decreased VMHC values in the thalamus. The results suggest that changes in functional homotopy in the CSTC circuitry may be involved in the pathophysiologic mechanism of OCD. Our findings provide new evidence of abnormalities in the CSTC circuitry in OCD.

Reduced Interhemispheric Functional Connectivity in Obsessive–Compulsive Disorder Patients

“…To explore the effect of SSRI on the homotopic connectivity, we compared the group difference in VMHC between SSRI-treated and drug-naive OCD patients and found no differences in VMHC in any brain region. The findings were consistent with a recent similar study (37); these results might imply the limited effect of medication on regulating abnormal VMHC in OCD. However, as this is a cross-section study, further prospect study comparing the same group of patients before and after treatment is thus necessary to elucidate the exact effect of medication on VMHC in OCD patients.…”

“…Similar to this study, Wang et al reported that patients with OCD had a lower VMHC in the CSTC circuitry (thalamus and OFC) than HCs, but no abnormal VMHC was found to be associated with the severity of clinical symptoms (after correction), nor was there a difference in VMHC between the SSRI-treated and drug-naive patients (37). However, inconsistent with this study, VMHC abnormalities in the fusiform gyrus/inferior occipital gyrus, lingual gyrus, and postcentral gyrus/precentral gyrus in OCD patients were not reported by Wang et al, which may be due to sample heterogeneity and analytical methods.…”

“…However, inconsistent with this study, VMHC abnormalities in the fusiform gyrus/inferior occipital gyrus, lingual gyrus, and postcentral gyrus/precentral gyrus in OCD patients were not reported by Wang et al, which may be due to sample heterogeneity and analytical methods. For example, in this study, we calculated the group differences in VMHC between OCD patients and HCs based on whole brain voxels, while Wang et al was based on the voxels that showed significant VMHC in any of the two groups (OCD patients and HCs) (37). To sum up, we found that OCD patients had significantly weaker homotopic RSFC than healthy controls, which is consistent with the findings in other various mental illnesses (11, 12, 14–17), meaning that homotopic RSFC abnormalities may be as critical pathophysiological features of mental illness as Rest state network (RSN) abnormalities are (38–41).…”

Decreased Resting-State Interhemispheric Functional Connectivity in Medication-Free Obsessive-Compulsive Disorder

“…A recent meta-analysis discovered that patients with OCD showed hypoactivation in the bilateral thalamus and medial OFC during inhibitory control ( 35 ). Decreased VMHC values in the OFC and thalamus in patients with OCD at rest were also observed in other studies ( 21 , 22 ). The present and previous studies supported the disconnection between homotopic brain regions within the CSTC circuits in patients with OCD, which might lead to obstacles in the communication and integration of cognitive and emotional information in OCD ( 15 ).…”

“…In this study, we investigated interhemispheric FC at rest in a relatively large number of medication-free patients with OCD using the VMHC method. We hypothesized that patients with OCD would exhibit decreased VMHC within and outside the CSTC circuits based on previous studies ( 21 , 22 ). We further explored the correlations between altered VMHC values and clinical variables in patients with OCD.…”