Corpus callosum macro and microstructure in late-life depression

Area of Science:

• Neuroimaging
• Neuroscience
• Geriatrics

Background:

• Corpus callosum (CC) morphology and microstructure differences are linked to late-life depression (LLD).
• Distinguishing between early and late-onset LLD may involve CC alterations.
• Multimodal imaging is crucial to differentiate microstructural changes from macrostructural effects.

Purpose of the Study:

• Investigate group differences in CC microstructure between depressed older adults and controls.
• Examine associations between CC measures and clinical features.
• Utilize advanced diffusion MRI (dMRI) models to assess CC integrity.

Main Methods:

• 107 older adults (55 depressed, 52 controls) underwent T1 MRI and dMRI.
• Analyzed 7 sub-regions of the mid-sagittal CC.
• Quantified white matter hyperintensities (WMH) and employed multi-tissue constrained spherical deconvolution (AFD) and diffusion tensor imaging (FA, RD).

Main Results:

• Callosal apparent fibre density (AFD) was lower in depressed patients.
• No significant group differences in CC thickness, surface area, FA, RD, or WMH volume.
• Late-onset depression correlated with lower FA, higher RD, and lower AFD.
• WMH volume associated with altered CC microstructure (lower FA/AFD, higher RD) in patients.

Conclusions:

• Corpus callosum structure is generally preserved in late-life depression.
• White matter hyperintensity burden significantly impacts CC microstructure in late-onset depression.
• Vascular pathology may contribute to microstructural changes in LLD, particularly in late-onset cases.