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. Author manuscript; available in PMC: 2019 Nov 1.
Published in final edited form as: Neurobiol Aging. 2018 Aug 1;71:161–170. doi: 10.1016/j.neurobiolaging.2018.07.018

Fig. 5. Increases in fractional anisotropy (FA).

Fig. 5.

(a) FA is known to increase in the superior corona radiata in Alzheimer’s disease relative to healthy controls. Images adapted from (Douaud et al., 2011). (b) DTI-FWE results show a FAt increase with healthy aging in the same regions, as well as in the internal capsule, occurring during healthy aging. Increased FA in healthy aging cannot be detected without FWE as it is seemingly masked by increasing isotropic free water with age. This suggests that increased FA is not a unique symptom of Alzheimer’s disease, but may represent an exaggeration of a normal age-related effect that can be observed even without FWE. Images displayed in LAS (radiological) orientation with fill to increase clarity. Abbreviations: DTI, diffusion tensor imaging; FA, fractional anisotropy; FWE, free water elimination.