The effect of normal aging on patterns of local cerebral glucose utilization.

When the fluorine-18-labeled fluorodeoxyglucose (18FDG) scan was applied to 40 normal volunteer subjects aged 18 to 78 years, mean local cerebral metabolic rate for glucose ( lCMRGlu ) declined with advancing age at a faster rate than was reported for mean local cerebral metabolic rate for oxygen. Slopes of decline with age were similar in the centrum semiovale, caudate nucleus, putamen, and overall frontal, temporal, parietal, and occipital cortex. Superior frontal cortex and posterior inferior frontal cortex were exceptions, undergoing more rapid metabolic decline with age than in other parts of the brain. Measurements of the rate constants for transport and phosphorylation process indicate that their change with aging had no major effect on the measurement of lCMRGlu by the 18FDG method.