Fig. 7.
Summary of identified patterns (A) and statistics (B) for all the diffusion metrics. A. In the DTI-derived metrics, higher tau-PET signal is consistently associated with decreased FA and increased MD, Da and Dr. In the NODDI-derived metrics, higher tau-PET signal is associated with decreased intracellular volume fraction (ICVF) (i.e. a proxy for axonal density). Increased OD was detected in very few (i.e. 2) pathways. Independent DDIS on Da and ICVF revealed similar patterns to that of MD. B. Statistics of the association patterns. “# pathways” denotes the total number of detected pathways, each of which contains a dual association between tau in both ends and a diffusion metric in the connection (i.e. color-coded connections in A). Adjusted r2diff describes the additional variance of tau-PET signal explained by a diffusion metric in the multivariate regression model that controls for age and sex in the detected pathways. Only significant r2diff (i.e., p < 0.05) were listed here. “Direction of change” denotes the direction of change in the diffusion metrics when tau-PET signal increases in the adjacent GM ROIs.