Memory and regional cerebral blood flow in mildly symptomatic Alzheimer's disease.

We performed SPECT perfusion imaging and memory testing with mildly and moderately demented Alzheimer's disease (AD) patients and with healthy controls. All patients had memory abnormalities, but 5 of the 21 patients had neither temporal nor parietal perfusion abnormalities, indicating that temporoparietal blood flow may be normal at a point when memory is pathologic and the clinical diagnosis of AD is possible.