Paradoxical hippocampus perfusion in mild-to-moderate Alzheimer's disease

The purpose of this study was to clarify the changes in hippocampal perfusion in mild-to-moderate Alzheimer's disease using PET and O-15-labeled water. Methods: Sixteen patients with probable mild-to-moderate Alzheimer's disease (age: 68.1 +/- 11.3 yr; MMSE: 21.1 +/- 4.5) and 10 normal volunteers (age: 65.1 +/- 8.2 yr) were studied. Regional cerebral blood flow (CBF) and cerebral blood volume (CBV) were measured using (15)0-labeled water autoradiographic method, (CO)-O-15-gas inhalation technique and PET. Results: Although the mean CBF in the parietotemporal region was significantly lower in the patient group than in the control group, the mean CBF in the hippocampus did not show significant reduction between the two groups, both in absolute and relative values. There was no significant regional CBV difference between the two groups. Parietotemporal perfusion correlated well with cognitive scores, both in absolute and relative values, in Alzheimer's disease, but hippocampal perfusion did not correlate well. Conclusion: Hippocampal perfusion was preserved in mild-to-moderate Alzheimer's disease.