Improved ability to diagnose Alzheimer disease (AD) at the earliest possible stage has the potential to lead to effective early interventions. William Jagust, MD, and colleagues hypothesized that baseline glucose metabolism and medial temporal lobe brain volumes would predict cognitive decline in normal older persons. The results of their study were published in the April 2006 issue of Annals of Neurology (Jagust W, et al. Ann Neurol. 2006;59:673-681).
The investigators tested 60 cognitively normal older adults (mean age 69.5 years) using [18F]fluorodeoxyglucose positron emission tomograpy (PET) and MRI scans. Monitoring the participants for an average of 3.8 years, they found an association between PET measures of glucose metabolism in the temporal and parietal cortices at the start of the study and the rate of decline on a test of global cognitive function. The authors, from the University of California at Berkeley, Lawrence Berkeley National Laboratory, and the University of Michigan, concluded that their findings suggest that PET and MRI have predictive value for cognitive decline but not specifically for AD—although the areas of the brain that predicted decline in their study are the same regions that have been associated with AD in the past.