Early detection of Alzheimer's disease: a statistical approach using positron emission tomographic data

Correlational analysis of regional cerebral glucose metabolism (rCMRglc) obtained by high-resolution positron emission tomography (PET) has demonstrated reduced neocortical rCMRglc interactions in mildly/moderately demented patients with probable Alzheimer's disease (AD). Thus, identification of individual differences in patterns of rCMRglc interactions may be important for the early detection of AD, particularly among individuals at greater risk for developing AD (e.g., those with a family history of AD). Recently, a statistical procedure, using multiple regression and discriminant analysis, was developed to assess individual differences in patterns of rCMRglc interdependencies. We applied this new statistical procedure to resting rCMRglc PET data from mildly/moderately demented patients with probable AD and age/sex-matched controls. The aims of the study were to identify a discriminant function that would (a) distinguish patients from controls and (b) identify an AD pattern in an individual at risk for AD with isolated memory impairment whose initial PET scan showed minor abnormalities, but whose second scan showed parietal hypometabolism, coincident with further cognitive decline. Two discriminant functions, reflecting interactions involving regions most involved in reduced correlations in probable AD, correctly classified 87% of the patients and controls, and successfully identified the first scan of the at-risk individual as AD (probability > 0.70). The results suggest that this statistical approach may be useful for the early detection of AD

Pattern of cerebral metabolic interactions in a subject with isolated amnesia at risk for Alzheimer's 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 dementia of the Alzheimer type. To verify if a similar rCMRglc pattern is present in subjects 'at risk' for Alzheimer's disease (AD), we used high-resolution PET to longitudinally study a subject with isolated memory 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 later, a follow-up evaluation did reveal reduced parietal rCMRglc values coinciding with a worsening of cognitive impairment, which suggested that standard analyses of resting rCMRglc data may not be useful in the early diagnosis of AD. In contrast, when a previously determined discriminant function for distinguishing controls from AD patients was applied, the subject was correctly identified as an AD patient on both PET scans