A Randomized, Double-blind, Placebo-controlled, Combined Single Ascending Dose and Multiple Ascending Dose Study

You may be eligible if

• Inclusion:
• 1. Clinical diagnosis of probable mild to moderate Alzheimer's disease (AD) by National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association Alzheimer's (NINCDS-ADRDA) criteria.
• 2. A Mini Mental State Examination (MMSE) score of 16 to 28, inclusive, at Screening. Subjects recruited to the first 2 SAD cohorts should have an MMSE of \> 22.
• 3. Where symptomatic treatment of Alzheimer's disease (AD) is clinically indicated, subjects must be on stable treatment (e.g., with an anticholinesterase inhibitor \[AChEI\] and/or memantine) for at least 12 weeks prior to the Screening visit.
• 4. On stable doses of all other prescribed medications for at least 4 weeks prior to the screening visit.
• Exclusion:
• 1. Any neurological condition that could be contributing to cognitive impairment above and beyond that caused by the subject's Alzheimer's disease (AD).
• 2. Any psychiatric diagnosis or symptoms, e.g hallucinations, major depression, or delusions, that could interfere with assessment of cognition in the subject.
• 3. History of transient ischemic attack (TIA), stroke, or seizures within 12 months of Screening.
• 4. Evidence of infection, tumor, stroke or other clinically significant lesions that could indicate a dementia diagnosis other than AD on brain magnetic resonance imaging (MRI) at Screening.
• 5. Other significant pathological findings on brain MRI at Screening, including but not limited to: more than 3 micro-hemorrhages, single macro-hemorrhage; evidence of vasogenic edema; evidence of cerebral contusion, encephalomalacia, aneurysms, vascular malformations or space occupying lesions.