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Fig. 3 | Alzheimer's Research & Therapy

Fig. 3

From: Diffusion imaging changes in grey matter in Alzheimer’s disease: a potential marker of early neurodegeneration

Fig. 3

A simplified schematic representation of molecular diffusion in and around neurons, and how this may change over time in Alzheimer’s disease (AD). a In the early presymptomatic stage water molecules are able to diffuse normally, with the mean diffusivity (MD) being the same as a normal healthy individual. b Evidence from familial AD studies suggests that in the period shortly before symptom onset the MD falls, implying that diffusion is restricted. This restriction may be a result of cellular hypertrophy and/or inflammation, in response to amyloid deposition in the presymptomatic phase. c During the symptomatic phase, progressive cellular atrophy results in a breakdown in the usual barriers to diffusion, with studies showing an increase in MD compared with normal controls. The effects in (c) are likely to progressively outweigh the effects in (b) as the disease progresses

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