Fibre-specific white matter changes in anorexia nervosa.

Area of Science:

• Neuroimaging
• Neuroscience
• Psychiatry

Background:

• White matter (WM) abnormalities are documented in anorexia nervosa (AN).
• Previous studies predominantly used diffusion tensor imaging (DTI), which has limitations in resolving complex fiber arrangements.
• Fixel-based analysis (FBA) offers enhanced anatomical specificity and interpretability for WM abnormalities.

Purpose of the Study:

• To investigate fiber-specific WM abnormalities in acute AN using FBA.
• To compare FBA findings with traditional DTI metrics in AN patients.
• To identify brain regions and potential pathological mechanisms underlying AN.

Main Methods:

• Diffusion-weighted imaging scans were acquired from 26 acute AN patients and 31 healthy controls.
• Fixel-based analysis (FBA) was employed to assess WM integrity.
• Diffusion tensor imaging (DTI) metrics were also calculated and compared between groups.

Main Results:

• FBA identified significant reductions in fiber-bundle cross-section in the anterior corona radiata and genu of the corpus callosum in AN patients, indicating morphological atrophy.
• These affected tracts connect brain regions implicated in AN symptomatology.
• DTI revealed increased axial diffusivity in the cerebellar peduncles of AN patients, with no significant differences in other DTI metrics. No overlap was found between FBA and DTI findings.

Conclusions:

• FBA is a powerful tool for detecting WM abnormalities in AN that may be missed by DTI.
• Morphological atrophy in specific WM tracts, particularly the anterior corona radiata and genu of the corpus callosum, is evident in AN.
• Myelin loss is suggested as a contributing factor to the observed WM abnormalities and clinical presentation in AN.