Longitudinal trajectories of verbal memory performance as a function of amyloid pathology. (a) Autopsy studies. (b) In vivo [11C]Pittsburgh Compound-B (PiB) imaging studies. (a) Reproduced with premission from Driscoll and colleagues , showing similar longitudinal trajectories of verbal memory performance (z-scores of free recall on the Cued Selective Reminding Test) in normal individuals with and without Alzheimer's disease (AD) pathology in contrast to marked decline in individuals who later are diagnosed with MCI or AD. (b) Adapted with permission from Resnick and colleagues  and shows differences in longitudinal trajectories of verbal memory performance (total immediate free recall on the California Verbal Learning Test) as a function of PiB retention. Note that individuals in the autopsy study are older than those in the imaging studies and are more likely to have passed through the risk period for cognitive impairment. MCI, mild cognitive impairment.