2463 - Alterations of white matter connectivity in the glaucomatous brain
Aims: Glaucoma is an optic neuropathy that can lead to permanent blindness. Although primarily considered an eye disease, glaucoma patients demonstrate neuroanatomical changes in brain regions associated with visual function as well as other areas1. Here, we perform multi-shell multi-tissue constrained spherical deconvolution-based2 whole-brain tractography on diffusion-weighted data to determine differences between patients and controls in their structural connectomes on a global and local scale.
Methods: Diffusion-weighted and T1 images of age-matched glaucoma patients (N=11) and controls (N=11) were acquired with a 3T MRI. Diffusion data was preprocessed in FSL and T1 images were parcellated in FreeSurfer using the Glasser atlas3 containing 360 cortical and 19 subcortical regions. Anatomically constrained probabilistic whole-brain tractography was performed for each individual in Mrtrix3. Graph theory measures were derived from the fractional anisotropy (FA) based connectivity matrices using the brain connectivity toolbox4 and statistically compared between groups with the Kruskal-Wallis test.
Results: Connectivity matrices contained 379 nodes with edges representing connectivity strength. Preliminary results reveal a reduced mean degree across the entire connectome in glaucoma subjects (M=127.81, SD=23.16) compared to controls (M=141.75, SD=22.65) with p=0.03.
Conclusions: These preliminary results point towards a change in the white matter architecture on a global scale. This supports the notion that glaucoma may be considered a more wide-spread neurodegenerative disease. Further analysis will possibly determine if global disturbances are due to alterations of specific nodes.
1Frezzotti et al (2016) Hum Brain Mapp,37(12):4581-4596.
2Tournier et al (2007) NeuroImage 35:1459-1472.
3Glasser et al (2016) Nature 536(7615):171-178.
4Rubinov et al (2010) NeuroImage 52:1059-69.