Relationship between Blood Flow Kinetics and Severity of Alzheimer’s Disease: Assessment of Severity Using a Questionnaire-Type Examination, Alzheimer’s Disease Assessment Scale, Cognitive Sub-Scale (ADAScog)

We assessed hemokinetics associated with changes in Alzheimer’s disease (AD) severity in 90 AD patients by researching the relationship between AD Assessment Scale, cognitive sub-scale (ADAS cog ) scores and regional cerebral blood flow (rCBF). In the present study, we employed the questionnaire-type ADAS cog examination to accurately assess the severity of AD. Between five groups classified on the basis of ADAS cog score, significant differences were observed in parietal, lateral temporal and superior frontal rCBF. In addition, in parietal and lateral temporal regions, significant correlations were also observed between ADAS cog score and rCBF. In superior frontal rCBF, significant differences were noted only between group 5 (≥40 ADAS cog points) and each of the other groups; there was no significant correlation between rCBF and ADAS cog score. Thus, we propose the following mechanism for blood flow kinetics associated with changed severity: In an early stage of AD, blood flow in the medial temporal cortex is impaired, and gradually involves the temporoparietal regions. While the medial temporal impairment of blood flow reaches a plateau, temporoparietal blood flow continues to be impaired well into a severe stage, at which point blood flow impairment in the frontal region is initiated.