This research study will assess whether AAB-001 is safe, well tolerated and effective for use in patients with Alzheimer's Disease. AAB-001 is a new drug that is not available outside this study. AAB-001 is an antibody (a type of protein usually produced by white blood cells to destroy other substances in the body). In Alzheimer's disease a protein called amyloid gathers in the brain and is thought to cause symptoms like memory loss and confusion. It is hoped that AAB-001 will attach to the amyloid protein in your brain and help your body to remove it.

Inclusion Criteria:

• Diagnosis of probable AD
• Age from 50 to 85 years, inclusive
• Rosen Modified Hachinski ischemic score less than or equal to 4
• Magnetic Resonance Imaging (MRI) scan consistent with the diagnosis of AD
• Fluency in English
• Stable doses of medications

Exclusion Criteria:

• Significant neurological disease other than AD
• Major psychiatric disorder
• Significant systemic illness
• History of stroke or seizure
• Weight greater than 120kg (264 lbs.)
• History of autoimmune disease
• Smoking more than 20 cigarettes per day
• Anticonvulsants, anti-Parkinson's, anticoagulant, or narcotic medications
• Prior treatment with experimental immunotherapeutics or vaccines for AD
• Presence of pacemakers or foreign metal objects in the eyes, skin, or body