This study will evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of R1450 in patients with mild to moderate Alzheimer Disease. Patients will be randomized to receive either R1450 or placebo by intravenous infusion for a total of 7 doses. The starting dose will be escalated in subsequent cohorts of patients in an adaptive manner, after a satisfactory assessment of safety, tolerability and pharmacokinetics of the previous dose. The anticipated time on study treatment is 3-12 months, and the target sample size is <100 individuals.

Inclusion Criteria:

• adult patients, 50-90 years of age;
• diagnosis of probable Alzheimer Disease, with symptoms >=1 year prior to screening;
• meets DSM-IV criteria for Alzheimer-type dementia;
• stabilised on approved medications for treatment of Alzheimer Disease for >=4 months prior to baseline.

Exclusion Criteria:

• active major depressive disorder, or a history of bipolar disorder;
• history of schizophrenia;
• concurrent participation in a non-pharmacological trial with a key objective of improving cognition;
• prior randomisation in any R1450 trial.