Study to Assess Brain Uptake and Safety of AH110690 (18F) Injection in Subjects with Probable Alzheimer's Disease, Amnestic Mild Cognitive Impairment and Healthy Volunteers.

Inclusion Criteria:

• The subject meets National Institute of Neurological and Communicative Disorders and Stroke; Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria for clinically probable AD and Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) criteria for dementia of Alzheimer's type.
• The subject meets Petersen criteria for amnestic MCI.
• The subject has no evidence of cognitive impairment by medical history.

Exclusion Criteria:

• The subject may not be able to complete the study as judged by the investigator.
• The subject has received ionising radiation exposure from clinical trials in the last 12 months or has participated in any other clinical study within 30 days of study entry.
• The subject has known allergies to [18F]AH110690 or [11C]PIB or their constituents.
• The subject is pregnant or breast-feeding.
• The subject has a history of alcohol and/or drug abuse within the last 2 years based upon a review of medical records.
• The subject has a contraindication for MRI (including, but not limited to, claustrophobia, pacemaker, presence of metallic fragments near the eyes or spinal cord, or cochlear implant).
• The subject has a history of head injury with loss of consciousness.