Macroscopic blood flow is reduced in early Alzheimer's disease dementia, independent of brain volume

Motivation: Mounting evidence suggests that cerebrovascular health is influential in Alzheimer's disease (AD), however little is known about macroscopic blood flow alterations in AD and those at increased risk of developing dementia. Goal(s): To determine if macroscopic blood flow in the major vessels of the brain decreases in early AD and Mild Cognitive Impairment (MCI). And if so, is a reduction in blood flow associated with brain volume? Approach: Macrovascular flow was measured using 4D Flow MRI at 3T in control, MCI and AD participants. Results: Mean blood flow was reduced in AD participants compared to controls in the MCA, PCA and basilar. Impact: Reductions in microscopic cerebral perfusion are reasonably well documented in Alzheimer's disease. However, we find reductions in macroscopic blood flow (using 4D Flow) in the larger feeding vessels of the brain, suggesting new investigations of upstream flow alterations are warranted.