A Study to Evaluate Safety, Tolerability, Plasma Drug Levels, and Cognitive Response Following Multiple Doses of a Drug in Healthy Elderly Participants.

Planned oral dose is PF-04447943, 5 mg q12 hours for 7 days.

Planned oral dose is PF-04447943, 15 mg q12 hours for 7 days.

Planned oral dose is PF-04447943, 35 mg q12 hours for 7 days. Actual dose may be adjusted based on pharmacokinetic and other data from prior dose cohorts.

Planned oral dose is PF-04447943, 35 mg q12 hours for 7 days. Actual dose may be adjusted based on pharmacokinetic and other data from prior dose cohorts.

Planned oral dose is PF-04447943, 35 mg q12 hours for 14 days. Actual dose may be adjusted downward based on pharmacokinetic and other data from prior dose cohorts.