White matter tracts associated with alexithymia and emotion regulation: A diffusion MRI study

Background: Alexithymia is a cognitive-affective impairment, suggested to be associated with emotion regulation. Herein, we investigated white matter (WM) tracts with Diffusion Magnetic Resonance Imaging (DMRI) connectometry approach using quantitative anisotropy (QA) tractography to discover possible associations between the emotion identification and regulation patterns and WM tracts. Methods: DMRI data were acquired from 218 healthy subjects aging 39.15 ± 20.19 who filled the Toronto Alexithymia Scale (TAS) and emotion regulation questionnaire (ERQ) from the LEMON dataset. Connectometry analysis was applied on WM tracts in DMRI images. Results: DMRI connectometry analysis revealed a significant correlation between TAS identification score and increased microstructural connectivity in WM pathways, including the body of corpus callosum (CC), bilateral fornix, and left arcuate fasciculus (AF) in males (FDR = 0.028), and corticospinal and cingulum tracts in females (FDR = 0.026). Furthermore, we found a significant positive correlation between overall TAS score and fornix properties in men (FDR = 0.026) and corticospinal tracts in women (FDR = 0.028). Middle cerebellar peduncle negatively correlated with describing emotion (FDR = 0.025) and the splenium of the CC and corticospinal tracts negatively correlated with this subscale (FDR = 0.049) in male group. However, the splenium of the CC, corticospinal tracts, and left AF positively associated with this subscale (FDR = 0.029). The splenium of the CC was negatively related to externally-oriented thinking among men (FDR = 0.038). Our results showed marginally associations between ERQ and similar WM tracts. Conclusion: Certain WM microstructures significantly correlate with emotion identification and regulation. These tracts are associated with specific somatosensory areas, language processing areas, and limbic area.