The purpose of this study is re-read of brain amyloid positron emission tomography (PET) scans acquired in previous florbetapir F 18 clinical studies by readers trained using updated reading methodology. The scans in this study came from subjects who had an autopsy to reveal the subject's true amyloid status.

Inclusion Criteria (Study A07[NCT00857415]):

• Have a projected life expectancy of ≤ 6 months as determined by the principal investigator (e.g. terminal medical condition) or are already enrolled in a longitudinal study of aging with an autopsy component;
• Can tolerate a 10 minute PET scan; and
• Give informed consent for study procedures and brain donation consistent with the legal requirements of the State in which they are enrolled and the State in which they die.

Exclusion Criteria (Study A07[NCT00857415]):

• Have primary brain tumor, known metastases to the brain, central nervous system (CNS) lymphoma;
• Have any major, focal structural loss of brain matter;
• Are aggressively being treated with life sustaining measures (e.g. currently on respirator; receiving high dose chemotherapy);
• Have a clinically significant infectious disease, including Acquired Immune Deficiency Syndrome (AIDS), Human Immunodeficiency Virus (HIV) infection, previous positive test for hepatitis or HIV or Creutzfeldt-Jakob disease (CJD);
• Are receiving any investigational medications, or have participated in a trial with investigational medications within the last 30 days;
• Have ever participated in an experimental study with an amyloid targeting agent (e.g. anti-amyloid immunotherapy, secretase inhibitor);
• Have had a radiopharmaceutical imaging or treatment procedure within 7 days prior to the study imaging session; or
• Are females of childbearing potential who are pregnant or not using adequate contraception.

No subjects received florbetapir in this study. This study consisted of rereads of scans previously acquired in another clinical study (A07).