DIFFERENCE OF REGIONAL CEREBRAL METABOLIC PATTERN BETWEEN PRESENILE AND SENILE DEMENTIA OF THE ALZHEIMER-TYPE - A FACTOR-ANALYTIC STUDY

Positron emission tomographic studies using metabolic ratios to repres ent the contrast between certain brain regions have shown differences of cerebral glucose metabolism between presenile and senile dementia o f Alzheimer type (DAT). In this study, factors for regional variance o f cerebral metabolism in 61 patients with probable Alzheimer's disease were obtained using principal component analysis (PCA). The differenc e between two age groups of DAT patients according to age at onset les s than or equal to 65 years (n = 30) and > 65 years (n = 31) were inve stigated. A PCA using nine pairs of cerebral regions normalized to cer ebellum for reduction of intersubject variability identified five regi onal factors for cerebral metabolism: one each for the left and right temporo-parietal cortex, and the other three for frontal cortex, prima ry visual and sensorimotor cortex, and mesial temporal cortex. The age groups differed significantly only in the factor for the right tempor o-parietal cortex, with a more prominent metabolic reduction in presen ile than senile DAT. Severity of dementia was correlated with the fact ors for the right and left temporo-parietal cortex. The effect of age at onset on glucose metabolism of the right temporo-parietal cortex wa s independent from that of dementia severity in DAT.