The detection of white matter alterations in obsessive–compulsive disorder revealed by TRActs Constrained by UnderLying Anatomy (TRACULA)

Abstract

Purpose

In recent years, a large number of studies have investigated obsessive–compulsive disorder (OCD) using diffusion-weighted images (DWIs) and have reported microstructural abnormalities in various regions, mainly the corpus callosum and cingulum. In the present study, we aimed to detect microstructural changes in the white matter using whole-brain tractography.

Patients and methods

We obtained MRI data from 25 adult non-medicated OCD patients and 27 healthy controls. DWI data from MRI scans were analyzed by the automated probabilistic tractography method referred to as TRActs Constrained by UnderLying Anatomy (TRACULA). We investigated diffusivity parameters: fractional anisotropy, radial diffusivity (RD), axial diffusivity, and mean diffusivity in 18 major white matter tracts and examined indices to know which measurements in which fibers can predict the diagnosis of OCD.

Results

Compared to healthy controls, OCD patients had significantly increased RD in the forceps major and a reduction of RD in the right cingulum angular (infracallosal) bundle. There was no correlation between these values and the clinical features.

Conclusion

We found RD alterations in the forceps major and the right cingulum angular (infracallosal) bundle, which might be associated with myelination changes in the temporal and occipital regions in OCD. Our results suggest that the pathogenesis of OCD may include abonormality of myelination status in not only the fronto-striato-thalamic circuit but also the posterior and temporal regions.

Keywords:

• tractography
• radial diffusivity
• forceps major
• cingulum

Acknowledgments

We thank T Okada, H Ito, and technical engineers for their assistance in MRI data acquisition. This work was partly supported by the “Application of DecNef for development of diagnostic and cure system for mental disorders and construction of clinical application bases” of the SRPBS from MEXT and AMED, JSPS KAKENHI Grant Numbers 25119001, 26120721 and 16K19778, and the Joint Usage/Research Center at ISER, Osaka University.

Author contributions

All authors contributed toward data analysis, drafting and revising the paper and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.