Phase III Study of the Correlation Between Florbetapir F18 PET Imaging and Amyloid Pathology in the Brain

There will be two primary analyses: * The first primary analysis will evaluate the correlation between the blinded readers' rating of amyloid plaque density on the PET scan and the cortical amyloid plaque density at autopsy. * The second primary analysis will evaluate the specificity of the blinded readers' rating of presence or absence of amyloid plaque density on the PET scan For the autopsy population, subjects will be enrolled from various end-of-life (e.g. hospice / hospital / nursing home) and late-life (longitudinal studies of aging) populations. Enrollment will include subjects with various levels of cognitive status, ranging from cognitively normal through dementia. It is expected that amyloid plaque density in this elderly population will range from very low (normal aging) through moderate (e.g. cognitively normal subjects with asymptomatic amyloid deposits or mild cognitive impairment (MCI) subjects with intermediate levels of amyloid deposits) to very high (subjects with AD). The study will also enroll younger healthy subjects presumably devoid of amyloid in the specificity cohort. Screening assessments may take place over several days and will include collection of demographic information, diagnostic interview, and safety assessments. At the time of screening, subjects or caregivers will be asked to provide consent for brain donation if they are not already enrolled in a brain donation program affiliated with this study, in addition to providing informed consent for the screening and imaging procedures in the study. Subjects who qualify for the study will have a catheter placed for intravenous (i.v.) administration of florbetapir F 18. Subjects will receive a single i.v. bolus of 370 MBq (10 mCi) of florbetapir F 18 followed by brain PET imaging for 10 minutes duration, beginning approximately 50 minutes post-injection. Vital signs and safety labs will be obtained prior to the administration of florbetapir F 18 and at the completion of the imaging session. Adverse events will be continuously monitored during the imaging session. Subjects who experience an adverse event will not be discharged until the event has been resolved or stabilized.