This registry will be used to identify patients who have etiology diagnosed or suspected to be Alzheimer's disease and positive amyloid scans, and have indicated their interest in being contacted for an Eli Lilly and Company (Lilly) Alzheimer's Disease drug research trial.

Inclusion Criteria:

• Male or female patients ≥ 50 years of age at the time of consent;
• Patients who have objectively verified cognitive impairment and etiology diagnosed or suspected to be Alzheimer's disease;
• Patients who are willing to make available to Avid a positive amyloid scan, or if an amyloid scan is not available, are willing to undergo amyloid scanning via the Florbetapir F 18 PET Scan Addendum;
• Patients who are willing to be contacted for possible participation in Lilly drug research trials targeting Alzheimer's disease;
• Patients who give informed consent or have a legally authorized representative (LAR) to consent for enrollment; and
• Patients who have a partner (informant) who is willing to participate as a source of information and has at least weekly contact with the patient (contact can be inperson, via telephone or electronic communication). The informant must have sufficient contact such that the referring physician feels the informant can provide meaningful information about the patient.

Exclusion Criteria:

• Patients who have a Mini Mental State Examination (MMSE) score of < 16;
• Patients who have an amyloid-negative PET scan (either a historical scan or scan via the Florbetapir F 18 PET Scan Addendum);
• Patients who have serious or unstable medical conditions that would exclude completion of all procedures and data collection for the registry, or would be likely to preclude participation in a drug research trial;
• Patients who are currently participating in a clinical trial with an investigational agent; or
• Patients who, in the opinion of the physician, are otherwise unsuitable for this registry.

Patients who have a) objectively verified cognitive impairment and etiology diagnosed or suspected to be Alzheimer's disease and b) a willingness to make available to Avid a preexisting amyloid scan that has been interpreted as positive, or if an amyloid scan is not available, a willingness to undergo amyloid scanning via the Florbetapir F 18 PET Scan Addendum, will be enrolled.