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