Association between brain functional failure and dementia severity in Alzheimer's disease: Resting versus stimulation PET study

Objective: This study tested the hypothesis that regional cerebral glucose metabolism during neuronal activation is a more sensitive index of neuronal dysfunction and clinical severity in Alzheimer's disease than is glucose m etabolism at rest. Methods: The subjects were 15 Alzheimer's disease patien ts with a wide range of Mattis Dementia Rating Scale scores (23-128). By us ing positron emission tomography, absolute glucose metabolism was measured in the parietal, occipital (visual areas), and temporal (auditory areas) co rtical regions during rest (eyes/ears covered) and audiovisual stimulation. Results: In the parietal cortex, glucose metabolism correlated with dement ia severity in both conditions. In contrast, in the relatively preserved vi sual and auditory cortical regions, glucose metabolism predicted dementia s everity during stimulation but not at rest. Conclusions: These findings sug gest that regional cerebral glucose metabolism during stimulation is a more sensitive index of the functional/metabolic failure of neuronal systems th an is metabolism at rest.