Predominant abnormality in cerebral glucose utilization in late-onset dementia of the Alzheimer type: a cross-sectional comparison against advanced late-onset and incipient early-onset cases.

Global cerebral blood flow and the cerebral metabolic rates of oxygen, CO2, glucose and lactate were studied in 11 patients aged 61-78 years who had been clinically diagnosed as suffering from incipient late-onset dementia of the Alzheimer type (DAT), and in 7 patients aged 66-83 years, in whom advanced late-onset DAT had been diagnosed, using the Kety-Schmidt technique. In incipient late-onset DAT, the predominant abnormality was a 45% reduction in cerebral glucose utilization, whereas cerebral blood flow and the cerebral metabolic rate of oxygen were diminished by only 17% and 18%, respectively. A severe imbalance between oxygen utilization and glucose utilization thus became obvious. In contrast, in advanced stages of late-onset DAT, this imbalance between oxygen and glucose utilization rates in the brain became smaller and smaller, and cerebral blood flow diminished markedly; these biological brain parameters finally all settled down at between 55% and 65% of the corresponding control values. The predominant abnormality in brain glucose utilization in incipient late-onset DAT may be associated with an impairment of its control mechanism(s), which are assumed to be either an influence of brain insulin action, or brain insulin receptor function, or both.