This study in individuals with mild to moderate Alzheimer's Disease is designed to assess:(1) safety and tolerability (2) the capacity of subcutaneous bapineuzumab to reduce brain amyloid load as measured by positron emission tomography (PET) scans.

Inclusion Criteria:

• Diagnosis of probable AD
• Age from 50 to less than 89
• Mini-Mental Status Exam score of 18-26 inclusive
• Brain magnetic resonance imaging (MRI) scan consistent with the diagnosis of AD
• Stable doses of medications (cholinesterase inhibitors and memantine allowed)
• Caregiver able to attend all clinic visits with patient
• Amyloid burden on screening PET scan consistent with diagnosis of AD

Exclusion Criteria:

• Significant neurological disease other than AD
• Major psychiatric disorder
• Significant systemic illness
• History of stroke or seizure, autoimmune disease, myocardial infarction within the last 2 years
• Smoking greater than 20 cigarettes per day
• Anticonvulsants, anti-Parkinson's, anticoagulant, or narcotic medications
• Prior treatment experimental immunotherapeutics or vaccines for AD
• Women of childbearing potential
• Presence of pacemakers, CSF shunts, or foreign metal objects in the eyes, skin or body