PATTERN OF CEREBRAL METABOLIC INTERACTIONS IN A SUBJECT WITH ISOLATEDAMNESIA AT RISK FOR ALZHEIMERS-DISEASE - A LONGITUDINAL EVALUATION

A pattern of reduced cerebral metabolic rate for glucose (rCMRglc) has been shown by positron emission tomography (PET) in patients with dem entia of the Alzheimer type. To verify if a similar rCMRglc pattern is present in subjects 'at risk' for Alzheimer's disease (AD), we used h igh-resolution PET to longitudinally study a subject with isolated mem ory impairment and a family history for autosomal dominant AD. Initial rCMRglc data did not reveal any consistent abnormality as compared to a group of sex- and age-matched healthy controls. However, 1 year lat er, a follow-up evaluation did reveal reduced parietal rCMRglc values coinciding with a worsening of cognitive impairment, which suggested t hat standard analyses of resting rCMRglc data may not be useful in the early diagnosis of AD. In contrast, when a previously determined disc riminant function for distinguishing controls from AD patients was app lied, the subject was correctly identified as an AD patient on both PE T scans.