This is a multiple vaccination study to find out if it is a safe treatment and what effects it has on the symptoms of early Alzheimer's disease in male and female patients aged 50 to 80 years. Approximately 40 study sites in Europe will be involved. Patients will be randomized to receive either AFFITOPE AD02 or placebo. Each patient's participation will last 1 year.

AFFITOPE AD02 is a second generation AD immunotherapeutics targeting Aβ. Its active component is a synthetic peptide functionally mimicking the unmodified N-terminus of Aβ.

Inclusion Criteria:

• Informed consent capability
• Early AD, based on episodic memory deficit and hippocampal atrophy
• Age from 50 to 80, inclusive
• MMSE of 20+
• Brain magnetic resonance imaging scan consistent with the diagnosis of AD
• Stable doses of medications (cholinesterase inhibitors and memantine allowed)
• Caregiver able to attend all visits with patient

Exclusion Criteria:

• Significant neurological disease other than AD
• Major psychiatric illness
• Significant systemic illness
• Autoimmune disease
• Prior treatment with experimental immunotherapeutics for AD including IVIG
• Women of childbearing potential without birth control
• Contraindication for MRI scan