Brain metabolism in Alzheimer's dementia: studies of 11C-deoxyglucose accumulation, CSF monoamine metabolites and neuropsychological test performance in patients and healthy subjects.

Abstract

Thirteen patients with dementia of Alzheimer type and nine age-matched control subjects were examined by a battery of neuropsychological tests and by positron emission tomography (PET) with 11C-deoxyglucose as a tracer for regional glucose metabolism in the brain. Concentrations of the monoamine metabolites HVA, MHPG and 5-HIAA were determined in the CSF from patients and controls. In the patients there was a diminished glucose metabolism in posterior parietal and superior temporal cortex areas to 60% of control levels. Other cortical areas showed similar changes, whereas the pre- and postcentral area, the cerebellum, the hippocampus and the basal ganglia showed less or no change. The decline in cortical metabolism in the patients was symmetrical but the variation in the left/right ratio was greater than in the controls. The CSF levels of monoamine metabolites did not differ between patients and controls. High levels of the metabolites were associated with low rates of glucose metabolism, possibly due to inhibitory influences of monoaminergic pathways upon cortical and subcortical neurons. The rate of glucose metabolism correlated positively with the neuropsychological test performance in both patients and controls. Verbal and memory performances were associated with greater left hemisphere metabolism in the patients, but not in the controls, whereas non-verbal abilities tended to be associated with right hemisphere metabolic dominance.