Microstructural brain assessment in late-life depression and apathy using diffusion MRI multi-compartments models and...

Area of Science:

• Neuroimaging
• Geriatric Psychiatry
• Cognitive Neuroscience

Background:

• Late-life depression (LLD) is common, disabling, and increases dementia risk.
• Apathy is associated with cognitive decline, but its underlying mechanisms in LLD are unclear.
• Diffusion Tensor Imaging (DTI) has limitations in accurately assessing white matter microstructure.

Purpose of the Study:

• To investigate novel diffusion model biomarkers for LLD and apathy using a multi-compartment model.
• To explore the relationship between apathy and white matter microstructure in specific fiber bundles.
• To identify new biomarkers for LLD and apathy, potentially revealing apathy's role in cognitive decline.

Main Methods:

• A tract-based approach interpolating microstructural metrics along fiber bundles.
• Inclusion of 56 individuals (35 LLD, 21 healthy controls).
• Multivariate statistical analysis combined with principal component analysis for data reduction.

Main Results:

• Identified statistical changes in diffusion MRI metrics in 5 different tracts.
• Demonstrated classically reported white matter modifications in LLD.
• Reported new findings on the biological basis of apathy in LLD, implicating striato-premotor tracts.

Conclusions:

• Novel diffusion models provide enhanced biomarkers for LLD and apathy.
• Striato-premotor tracts may play a role in LLD and apathy.
• White matter alterations in specific tracts are linked to both motivation and cognition, suggesting apathy as a potential prodromal phase of neurodegenerative disorders.