The purpose of this study is to assess xaliproden's potential capacity of slowing the deterioration of cognitive and global functions in patients with mild to moderate Alzheimer's disease. The patients participating in this study will take orally once daily xaliproden or placebo (inactive substance pill).

Inclusion Criteria:

• Diagnosis of probable Alzheimer's disease using NINCDS-ADRDA criteria

  • Mild to moderate degree of severity of dementia as assessed by the Mini-Mental State Examination score of 16 to 26 (inclusive)
  • Potential participant may be treated with conventional Alzheimer's disease therapy and must be on stable dose for at least 6 months prior to the randomization and during the entire study period
  • Potential participant must have a reliable caregiver and must be living in a community or in an assisted living facility
  • Mother tongue is English, Spanish or French (oral and written fluency)
  • Signed informed consent from potential participant or legal representative and identified caregiver

Exclusion Criteria:

• Potential participant with any other cause of dementia.
• Potential participant with serious health problems other than Alzheimer's disease
• Use of an investigational drug within two months prior to randomization or during this study