[Longitudinal study of neuropsychological and cerebral blood flow changes in Alzheimer-type dementia]

To examine the correlation between neuropsychological and cerebral blood flow changes in Alzheimer-type dementia (AD), we studied 17 patients with AD longitudinally (intervals ranging from 12 to 40 months). AD patients were divided into a slowly-progressive group (S, 10 patients) and a rapidly-progressive group (R, 7 patients) on the basis of progression rates of symptoms. The perfusion ratio (%) (PR), defined as the activity density in regions of interest normalized to the mean activity density in unaffected regions (cerebellum, primary visual and sensory-motor cortex), was used as a measure of relative regional cerebral blood flow by SPECT. Hasegawa's dementia score (HDS) in both the first and last studies significantly correlated with PR of the temporoparietal lobe, but not PR of the frontal lobe. The PR of the frontal lobe in the first study was significantly decreased in R-group patients compared to S-group patients. However, there was no difference in PR of the temporoparietal lobe between the S and R groups. Though the change in PR (PR (last study-first study)/duration) in the frontal lobe was significantly less in R-group than in S-group patients, there was no difference in the change in PR in the temporoparietal lobe. These results suggest that the degree of intellectual impairment is related to the function of the temporoparietal lobe, that progression is related to function of the frontal lobe, and that frontal hypoperfusion on SPECT may predict relatively rapid intellectual deterioration.