Alzheimer's

Normal Brain Image / Alzheimer's Brain image W/ arrows

PET images show the metabolic degeneration of the brain of a patient with Alzheimer's as it progressively reduces brain function. In the early stages of the disease, limited areas of the brain are dysfunctional (arrows in upper image), but in late stages of Alzheimer's, larger brain areas are affected (arrows in upper and lower images). The structures that are spared and remain functioning (dark blue images) are the portions of the cortex that control the motor systems such as the legs, arms and hands (upper image), the internal structures (center structures that are dark blue in lower image) and the visual cortex at the back (bottom of the lower image). Notice that the metabolic function of the brain with late stage Alzheimer's resembles that of a child. This correlates with the child-like functional behavior of these patients.

A PET scan shows a very consistent diagnostic pattern for Alzheimer's disease where certain regions of the brain have decreased metabolism early in the disease (see arrows). In fact, the pattern often can be recognized several years before a physician is able to confirm the diagnosis and is also used to differentiate Alzheimer's from other confounding types of dementia or depression.