Shannon Chiu1, Robin Chen2, Wei-en Wang2, Melissa Armstrong1, Bradley Boeve3, Kejal Kantarci4, David Vaillancourt2
1University of Florida Department of Neurology, 2University of Florida Department of Applied Physiology and Kinesiology, 3Mayo Clinic Rochester Department of Neurology, 4Mayo Clinic Rochester Department of Neuroradiology
Objective:
To characterize longitudinal diffusion microstructural changes in individuals with dementia with Lewy bodies (DLB).
Background:
Diffusion-weighted MRI (dMRI) examines tissue microstructure integrity and white matter pathways in vivo. Prior DLB studies focused on white matter or voxel-based techniques. Less is known about longitudinal white and grey matter microstructural changes in DLB.
Design/Methods:
dMRI scans were collected on individuals with DLB from the Mayo Clinic Longitudinal Imaging Biomarkers of DLB Program. Demographics, clinical evaluations and MRI were collected at baseline, and 12 or 24 months. Free-water (FW) and FW-corrected fractional anisotropy (FAT) were analyzed in grey and white matter using 122 bilateral template regions and tracts of interest in Montreal Neurological Institute space. Primary outcomes were differences in FW and FAT between baseline and 12 or 24 months.
Results:
We identified 23 individuals with DLB from baseline to 12 months [mean age 69.3 years (SD 9.5); 95.8% male], and 16 individuals from baseline to 24 months [mean age 67.5 years (SD 9.3); 100% male]. Participants at both time-points showed worsening in Montreal Cognitive Assessment and Movement Disorders Society Unified Parkinson's Disease Rating Scale motor scores (p<0.05). We found significant differences in FW, but not FAT, from baseline to 12 months. Significant increases in FW at both time-points compared to baseline were observed in the insula, putamen, parahippocampal, and rolandic operculum regions (p<0.05). We found more widespread microstructural changes from baseline to 24 months, with increased FW in the amygdala, entorhinal, mid and posterior cingulum, inferior frontal, hippocampal, pallidum, precuneus and retrosplenial regions (p<0.05). We found decreased FAT from baseline to 24 months in the cerebellar and superior occipital regions (p<0.01).
Conclusions:
Longer follow-up at 24 months identified broader networks of free-water changes in individuals with DLB. More investigation is needed to evaluate the relationship of microstructural changes with clinical progression in DLB.