Microstructural alterations in the locus coeruleus-entorhinal cortex pathway in Alzheimer’s disease and frontotemporal dementia

METHODS: Diffusion-weighted MRI scans we recollected for 21 AD, 20 behavioral variants of FTD (bvFTD), and 20 controls. Fractional anisotropy (FA), mean, axial, and radial diffusivities (MD,AxD,RD) were computed in the LC-TEC pathway using a normative atlas.

Atrophy was assessed using cortical thickness and correlated with microstructural measures. RESULTS: We found (i) higher RD in AD than controls; (ii) higher MD, RD, and AxD, and lower FA in bvFTD than controls and AD; and (iii) a negative association between LC-TEC MD, RD, and AxD, and entorhinal cortex (EC) thickness in bvFTD (all p<0.050). DISCUSSION: LC-TEC microstructural alterations are more pronounced in bvFTD than AD, possibly reflecting neurodegeneration secondary to EC atrophy.