Figure 2.

Amyloid deposition in older adults measured by [¹¹C]PIB. The format is similar to Figure 1. The scale is a percentage of uptake above brainstem activity (see Materials and Methods). The top image shows nondemented older adults (n = 6) who have minimal amyloid deposition (PIB^-). There is nonspecific binding of [¹¹C]PIB in white matter. The middle image shows nondemented older adults (n = 2) who have significant amyloid deposition (PIB⁺), perhaps indicating preclinical AD. The bottom image shows demented older adults (n = 10). Notable amyloid deposition is apparent in medial and lateral posterior parietal regions, extending into precuneus, posterior cingulate, and retrosplenial cortex, as well as in frontal cortex along the midline. Medial temporal amyloid deposition is minimal. This pattern of amyloid deposition in AD is reliable across separate participants groups (supplemental Fig. 1, available at www.jneurosci.org as supplemental material).