Cerebral perfusion is globally reduced in Alzheimer's disease – The missing link?

Regional cerebral blood flow (rCBF) is reportedly reduced in brain areas affected by the Alzheimer disease (AD) histopathology, such as beta-amyloid plaques and neurofibrillary tangles (NFT), in particular temporal and parietal cortex. Therefore, reduced rCBF was usually interpreted as a consequence of lost neuronal activity caused by neurodegeneration. However, so far, such rCBF measurements were done by single photon emission computed (SPECT) or positron emission (PET) tomography with relative values of activity referring to overall global means or reference regions such as cerebellum within individuals. Metho…