White matter abnormalities in misophonia

Abstract

Misophonia is a condition in which specific ordinary sounds provoke disproportionately strong negative affect and physiological arousal. Evidence for neurobiological abnormalities underlying misophonia is scarce. Since many psychiatric disorders show white matter (WM) abnormalities, we tested for both macro and micro-structural WM differences between misophonia patients and healthy controls. We collected T1-weighted and diffusion-weighted magnetic resonance images from 24 patients and 25 matched controls. We tested for group differences in WM volume using whole-brain voxel-based morphometry and used the significant voxels from this analysis as seeds for probabilistic tractography. After calculation of diffusion tensors, we compared group means for fractional anisotropy, mean diffusivity, and directional diffusivities, and applied tract-based spatial statistics for voxel-wise comparison. Compared to controls, patients had greater left-hemispheric WM volumes in the inferior fronto-occipital fasciculus, anterior thalamic radiation, and body of the corpus callosum connecting bilateral superior frontal gyri. Patients also had lower averaged radial and mean diffusivities and voxel-wise comparison indicated large and widespread clusters of lower mean diffusivity. We found both macro and microstructural WM abnormalities in our misophonia sample, suggesting misophonia symptomatology is associated with WM alterations. These biological alterations may be related to differences in social-emotional processing, particularly recognition of facial affect, and to attention for affective information.

Keywords: Attention; Diffusion tensor imaging; Misophonia; Probabilistic tractography; White matter volume.

Fig. 1

Patients had greater white matter volumes than controls at (A) the left inferior fronto-occipital fasciculus/anterior thalamic radiation and (B) the left body of the corpus callosum/anterior thalamic radiation. Voxels with p-uncorrected < 0.001 are displayed according to neurological convention. (C) Population map of probabilistic tractography seeded from the white matter volume difference peak voxels depicted in subplot A (green) and B (violet). Only voxels are shown that contained at least 20 (out of 5000) streamlines and that were shared by at least 50% of subjects. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 2

Patients had widespread lower mean diffusivity than controls. (A) Voxels showing significantly lower mean diffusivity in patients (red; p-FWE < 0.05). (B) Significant voxels (black) displayed on the JHU White-Matter Tractography Atlas. Maps are shown according to neurological convention. ATR = Anterior Thalamic Radiation; ILF = Inferior Longitudinal Fasciculus; UF = Uncinate Fasciculus; IFOF = Inferior Fronto-Occipital Fasciculus; FMi = Forceps Minor; FMa = Forceps Major; CST = Cortico-Spinal Tract; SLF = Superior Longitudinal Fasciculus. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)