Figure 5.

PET images using fluorodeoxyglucose (FDG) radiotracer. This model involves 3 variables: age, percent decrease in glucose metabolism, and Mini Mental State Examination (MMSE) scores in individuals diagnosed with AD using a healthy control group as baseline comparison (note that a MMSE score 27 or greater indicates normal cognition). In this study, the authors reported that an increase in AD severity is negatively correlated with grey matter volume, glucose metabolism, and MMSE scores. They also mention that the greater percent decrease in glucose metabolism in younger AD patients is both due to the dissociation between early- and late-onset AD and the effect of normal healthy aging in elderly patients resulting in a lesser percent decrease ([61], reprinted with permission).