A Study of Two Doses of 18F-AV-45 in Alzheimer's Disease and Healthy Volunteers

Inclusion Criteria (AD group): * Greater than 50 years of age * Probable AD according to the National Institute of Neurological and Communication Disorders and Stroke-Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria * Mild/moderate dementia as evidenced by a Mini-Mental State Examination (MMSE) score ranging from 10 to 24, boundaries included, at screening * History of cognitive decline gradual in onset and progressive over a period of at least 6 months Inclusion Criteria (healthy volunteer group): * 35 to 55 years of age, inclusive * MMSE of 29 or greater Exclusion Criteria (both groups): * Neurodegenerative disorders other than AD, including, but not limited to Parkinson's disease, Pick's disease, fronto-temporal dementia, Huntington's chorea, Down syndrome, Creutzfeldt-Jacob disease, normal pressure hydrocephalus, and progressive supranuclear palsy * Diagnosis of other dementing / neurodegenerative disease * Diagnosis of mixed dementia * Cognitive impairment resulting from trauma, hypoxic damage, vitamin deficiency, brain infection, brain cancer, endocrine disease, or mental retardation * Clinically significant infarct or possible multi-infarct dementia as defined by the NINCDS criteria * Evidence on screening MRI or other biomarker that suggests alternate etiology for cognitive deficit (for healthy controls, evidence suggesting the presence of AD pathology) * Clinically significant psychiatric disease * History of epilepsy or convulsions * Clinically significant hepatic, renal, pulmonary, metabolic, or endocrine disturbances * Current clinically significant cardiovascular disease * Received investigational medication within the last 30 days