Evaluation of 3APS in Patients With Mild to Moderate Alzheimer's Disease

Inclusion Criteria: Patients may be included in this study if they meet all of the following criteria: * Male or Female (age 50 years and older): Female must be of non-childbearing potential (i.e. surgically sterilized or at least 2 years post-menopausal). * Diagnosis of probable Alzheimer's disease based on the National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA criteria). * Severity of dementia of mild to moderate degree as assessed by the Mini Mental State Examination (MMSE) performed at the screening visit. * Patient must be living in the community with a reliable caregiver. Participant living in an assisted living facility may be included if study medication intake is supervised and participant has a reliable caregiver. * Potential participant must be treated with conventional Alzheimer's disease therapies and must be on stable dose for at least 4 months prior to the screening visit and during the entire study period. * Fluency in English, French or Spanish (oral and written). * Signed informed consent from potential participant or legal representative and caregiver. Exclusion Criteria: Patients will not be eligible to participate in the study if they meet any of the following criteria: * Potential participant with any other cause of dementia. * Life expectancy less than 2 years. * Potential participant with a clinically significant and/or uncontrolled condition or other significant medical disease. * Use of an investigational drug within 30 days prior to the screening visit or during the entire study. * Previous use of 3APS. Patient recruitment is done by participating centers.