The following is a summary of the “Association of longitudinal cognitive decline with diffusion MRI in Gray Matter, Amyloid, and Tau deposition,” published in the January 2023 issue of Neurobiology of Aging by Wang, et al.
Alzheimer’s disease (AD) is initially diagnosed by extracellular amyloid plaques in grey matter, followed by abnormal accumulation of tau protein. However, cognitive decline, amyloid and tau pathology, and changes in grey matter diffusion all have unclear links. Therefore, T1-weighted imaging, diffusion MRI, and amyloid and tau PETs from the ADNI 2/3 database were first subjected to cross-sectional analyses.
In 171 individuals with no cognitive impairment, 103 with mild cognitive impairment, and 44 with Alzheimer’s disease, we measured cortical volume, free water, fractional anisotropy (FA), and amyloid and tau SUVRs. When the 3 groups were combined, the entorhinal cortex and hippocampus of amyloid-negative individuals showed decreased extracellular free water with increasing amyloid burden, while the entorhinal cortex and hippocampus of tau-positive individuals showed increased extracellular free water.
When comparing tau SUVRs (27%), T1 volume (36%), and amyloid SUVRs (75%), they found that diffusion measures (free-water, FA) alone had a high r-square value in predicting MMSE score 2 years later in the MCI subjects. One powerful non-invasive marker for foreseeing mental decline is diffusion measures.
Source: sciencedirect.com/science/article/abs/pii/S0197458022002299
