See termination reason in detailed description.

This study is designed to look at the potential for an investigational drug (PF-04995274, under development by Pfizer, Inc. as a potential treatment for Alzheimer's disease) to reverse changes in memory and learning/problem solving skills caused by co-administration of a marketed drug called scopolamine. Scopolamine is known to cause temporary changes in memory and learning/problem solving skills that are similar to those seen in people with alzheimer's disease(AD).

Changes in sponsor's organizational strategy have led to the decision to terminate the study and therefore to not conduct the second cohort (Cohort B/arms 2 and 3) . This decision was not based on significant safety concerns. Date of termination (ie, the date the site was notified to stop study activities) was 12 Oct 2011.

Inclusion Criteria:

• Healthy male or female volunteers; females must be of non-childbearing potential.
• Weight with normal limits for height.
• Willing to comply with study schedule and able to complete 2 practice sessions (pre-study) with computerized memory and learning/problem solving tests.

Exclusion Criteria:

• Positive urine drug screen; concurrent use of prescription or over-the-counter (OTC) drugs or dietary supplements within 7 days or 5 half-lives prior to the first dose of study medication.
• Use of medications with significant serotonergic, cholinergic or anticholinergic side effects [SSRIs, pyridostigmine, tricyclic antidepressants, meclizine, oxybutynin]) within 4 weeks of first dose of study drug.
• Glaucoma
• Abnormal electrocardiogram (ECG)
• Treatment with an investigational drug within 30 days of dosing.