Abnormal white matter structural connectivity in adults with obsessive-compulsive disorder

Abstract

Obsessive-compulsive disorder (OCD) is a complex and severe psychiatric disorder whose pathogenesis is not fully understood. Recent studies have shown white matter (WM) alterations in adults with OCD, but the results have been inconsistent. The present study investigated WM structure in OCD patients with the hypothesis that large-scale brain networks may be disrupted in OCD. A total of 24 patients with OCD and 23 healthy controls (HCs) were scanned with diffusion tensor imaging. A tract-based spatial statistics (TBSS) approach was used to detect differences across the whole brain in patients with OCD vs HCs; post hoc fiber tractography was applied to characterize developmental differences between the two groups. Relative to HCs, patients with OCD had lower fractional anisotropy (FA) values in the corpus callosum (CC), left anterior corona radiata (ACR), left superior corona radiata (SCR) and left superior longitudinal fasciculus (SLF), and higher radial diffusivity in the genu and body of CC. Among the TBSS de-projected region of interest results, compared with HCs, patients with OCD showed lower of the mean FA values of fiber bundles passing though the SLF, and shorter lengths of ACR, SCR and CC. In conclusion, this study provides novel evidence of widespread microstructural alterations in OCD and suggests that OCD may involve abnormalities affecting a broader network of regions than commonly believed.

Altered frontal interhemispheric and fronto‐limbic structural connectivity in unmedicated adults with obsessive‐compulsive disorder

“…Our finding of less FA in forceps minor in OCD compared to healthy participants replicates previous TBSS (Benedetti et al, 2013;Gan et al, 2017;Nakamae et al, 2011) and tractography (Oh et al, 2011) findings of altered integrity of corpus callosum in adults with OCD. Forceps minor connects the medial and lateral surfaces of frontal cortices, crossing the midline via the genu of the corpus callosum.…”

“…Previous tractography studies of adults with OCD have focused on specific tracts (Chiu et al, ; Oh et al, ) using deterministic tractography, a method that depends on the positioning of regions of interest and other factors (e.g., FA and angle threshold), leading to findings that might be difficult to replicate(Behrens, Berg, Jbabdi, Rushworth, & Woolrich, ). Other studies of OCD have limited their fiber tracking to regions that appeared to differ in FA across OCD and healthy participants in voxel‐wise or TBSS analyses (Gan et al, ; Peng et al, ). Such findings preclude our understanding of the integrity or connectivity of other fiber tracks in the brain.…”

White Matter Microstructure and its Relation to Clinical Features of Obsessive-Compulsive Disorder: Findings from the ENIGMA OCD Working Group

“…Since both the PTR and the SS convey projection fibers to the posterior part of the brain, our results support the idea that OCD involves abnormalities affecting a network of regions that is more extensive than commonly believed 1,52 . Both bundles project to posterior parietal, temporal and occipital cortices, and include many major association fibers (i.e., the inferior 1 9…”

“…A number of limitations of the data analyzed here deserve emphasis. First, although TBSS is a widely used method for voxel-based analysis of WM, addressing issues associated with smoothing and misalignment in DTI group analysis 52 , the technique has some limitations. Indeed, by reducing WM tracts into a skeleton, delineating the center of the tracts and projecting onto it only the highest FA value along the projection, some information might be lost 62 and potential artifacts, resulting from misregistration, might be produced 63 .…”

Event‐related EEG oscillations in body dysmorphic disorder

“…Thus, the most affected brain areas are the prefrontal and cingulate cortices. Indeed, recent studies 39 suggest that the diversity of EEG findings in OCD could be an indication of malfunctioning of the frontal-striatal-thalamic (FST) circuitry resulting in poor functional connectivity between different brain regions; as in the FST circuit, theta and alpha oscillations play an important role in maintaining functional connectivity. 40 The effects we identified in our results might potentially overlap with the aforementioned brain areas; however, advanced source reconstruction analysis is needed to confirm this speculation.…”