Quantitative MRI to understand Alzheimer's disease pathophysiology.

PURPOSE OF REVIEW: The role of white matter damage in the progression of Alzheimer's disease and the associated cognitive symptoms is becoming increasingly clearer. This is partly because of the advent of diffusion tensor imaging, which, in combination with other quantitative MRI techniques, offers unique insights into the patholophysiology of Alzheimer's disease in vivo. The purpose of this review is to integrate the most recent imaging findings, with respect to understanding Alzheimer's disease pathophysiology, and identifying potential biomarkers with diagnostic and prognostic value.

RECENT FINDINGS: Consistent with patterns of gray matter atrophy, white matter damage in Alzheimer's disease is localized within white matter tracts connecting the temporal lobe with the rest of the brain, including the cingulum, the uncinate fasciculus and the fornix. These abnormalities are often correlated with adjacent gray matter tissue loss, and with cognitive performance. The relationship between these findings and loss of functional connectivity supports the hypothesis of disconnection as a mechanism for the spread of Alzheimer's disease.

SUMMARY: White matter abnormalities occur early in Alzheimer's disease, and might actively contribute to the progression of the disease. Functional and structural gray matter abnormalities parallel the white matter changes, and successful biomarkers are likely to be multiparametric.