Figure 7.

The assumptions of pathological changes in AD spectrum. In SCD stage, the amyloid plaque and other risk factors might trigger the inflammatory process associated with increased microglia and astrocytes. These pathological processes eventually lead to increased cellular density and microenvironment complexity in hippocampal tissues, so the MK would increase. In MCI stage, the expanded extracellular space (due to the axonal and neuronal loss) outweighed the inflammation, so the water diffusion was not hindered but increased, and MD was increased. In AD stage, brain atrophy (neurodegeneration or neuronal body loss) will be predominant. AD = Alzheimer’s disease; SCD = subjective cognitive decline. We plotted this figure by ourselves. The ascending red arrow represents increase; the descending red arrow represents decline.