Glucose is an energy source for the brain and is essential to the survival of the cells. One technique to measure the health of brain tissue is to measure the distribution of glucose metabolism using fluorodeoxyglucose (FDG) PET imaging. In Alzheimer’s disease and other neurodegenerative disorders, glucose uptake is severely diminished in regions affected by the disease. FDG PET imaging is especially useful in investigating patients with dementing illnesses, and it may also offer clues as to how Aβ and tau affect the brain.