Effectiveness of Florbetapir (18F) PET Imaging in Changing Patient Management and the Relationship Between Scan Status and Cognitive Decline

Inclusion Criteria: Patients may be enrolled in the mild impairment (not demented) group if the following criteria are met: 1. Males or females ≥ 50 to \<= 90 years of age. 2. Have cognitive decline verified by a study partner or cognitive impairment verified by the study physician. 3. Have a study partner who provides separate consent and is willing to accompany the patient on all of the study visits. 4. Have an MMSE score of 24 to 30 inclusive. 5. Can tolerate a 10-minute PET scan. 6. Have the ability to cooperate and comply with all study procedures. 7. Have an enrolling physician who has less than high confidence in their diagnosis for the patient related to the cognitive decline at the time of enrollment. 8. Ability to provide informed consent for study procedures. Patients may be enrolled in the dementia group if the following criteria are met: 1. Are males or females ≥ 50 to \<= 90 years of age. 2. Meet clinical criteria for dementia. 3. Have a caregiver who provides separate consent and is willing to accompany the patient on all of the study visits. 4. Have an MMSE score of 16 to 24 inclusive. 5. Have not received a clinical examination and/or laboratory test results that strongly indicates a non-neurodegenerative cause for the patients cognitive impairment. 6. Can tolerate a 10-minute PET scan. 7. Have the ability to cooperate and comply with all study procedures. 8. Have an enrolling physician who has less than high confidence in their diagnosis for the patient related to the cognitive decline at the time of enrollment. 9. Ability to provide informed consent for study procedures. (If the patient is incapable of giving informed consent, the patient's legal representative may consent on behalf of the patient but the patient must still confirm assent. This person may serve as the study partner as well). Exclusion Criteria: Patients will be excluded from enrollment if they: 1. Have a current serious or unstable illness; 2. The patient or enrolling physician knows the result of a previous amyloid imaging scan; 3. The patient has a known brain lesion, pathology or alternative diagnosis that strongly explains the patient's clinical presentation; 4. Are receiving any investigational medications, or have participated in a trial with investigational medications within the last 30 days; 5. Have ever participated in an experimental study with an amyloid targeting agent (e.g. anti-amyloid immunotherapy, γ -secretase or β -secretase inhibitor) unless it can be documented that the patient received only placebo during the course of the trial; 6. Have had a radiopharmaceutical imaging or treatment procedure within 7 days prior to the study imaging session; or 7. Are females of childbearing potential who are not surgically sterile, not refraining from sexual activity or not using reliable methods of contraception. Patients will also be excluded from enrollment if their enrolling physician: 1. Does not consider Alzheimer's disease as a potential cause of the patient's cognitive decline. 2. Is not the primary physician taking care of the patient with respect to the management of their cognitive impairment. 3. Cannot categorize the patient as either: a) having a documented and completed evaluation for cognitive decline within the past 18 months old; or b) currently undergoing evaluation for cognitive decline. 4. Is unwilling to suspend all testing and other evaluation procedures between the time of the baseline evaluation of the enrolling physician's diagnosis and management plan and the time the completion of the PET scan.