Multiple Dose Study Evaluating the Safety and Tolerability of NSA-789

• Alzheimer Disease
• Healthy Subjects

• Drug: NSA-789
• Other: placebo

• Placebo Comparator: placebo
  
  Intervention: Other: placebo
• Experimental: NSA-789
  
  Intervention: Drug: NSA-789

Inclusion Criteria

• Men or women aged 18 - 50 years (healthy subjects) or greater than 55 years old (subjects with Alzheimer's Disease)
• Women must be surgically sterile or postmenopausal
• Subjects with Alzheimer's Disease must be generally healthy, but may have a stable, chronic illness if well controlled.

Exclusion Criteria

• Healthy subjects may not be on any prescription or investigation drugs within 30 days of start of study.
• Subjects with Alzheimer's Disease may not be on any cholinesterase inhibitors such as donepezil (Aricept®) or rivastigmine (Exelon®) within 4 weeks of the start of the study.