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Local rates of cortical glucose metabolism were estimated by positron emission tomography in 13 right-handed patients with Alzheimer's disease. Individuals with disproportionate failure of language function had markedly diminished metabolism in the left frontal, temporal, and parietal regions. Patients with predominant visuo-constructive dysfunction evidenced a hypometabolic focus in the right parietal cortex. Patients with memory failure as the most apparent feature had no significant metabolic asymmetry in cortical regions. In all subjects, verbal competency generally correlated with metabolic activity in the left frontal and temporal areas, while visuo-constructive test performance was linked to glucose utilization in the right parietal lobe.

Neuropsychological test performance and estimates of regional rates of cortical glucose metabolism obtained via positron emission tomography are presented for patients with Alzheimer's disease (AD). Analyses of these data indicated the presence of distinct subgroups characterized by qualitatively different profiles of cognitive impairment and corresponding patterns of cerebral hypometabolism. No subgroup differences were noted with regard to age at onset or reported duration of symptoms. These findings indicate that, in a given individual, AD may initially invade a relatively circumscribed cortical region. Thus, although AD may constitute a single disease process, it does not result in a unitary neuropsychological syndrome.