The primary outcome measure will be the one year change in the cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAScog). The attainment of significant endpoints will be examined as a secondary outcome measure. Other secondary measures include the CDR sum-of-boxes, Neuropsychiatric Inventory, the Quality of Life-AD and the ADCS pharmacoeconomic scale. The influence of HLA-DR (Human Leukocyte Antigen) genotype on clinical progression and response to treatment will also be examined.