This is a first-in-human study of GSI-136, a gamma-secretase inhibitor being developed for the treatment of Alzheimer disease. This study will take place in Japan only and will provide an initial assessment of the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of GSI-136 after administration of ascending single oral doses to healthy Japanese male subjects and healthy Japanese elderly male subjects.

Inclusion Criteria .

1. Men aged 20 to 45 years, or greater than 65 years, inclusive, at screening and who agree to use a medically acceptable form of contraception during the study and to continue its use for 12 weeks after test article administration.
2. Healthy as determined by the investigator on the basis of medical history, physical examination, clinical laboratory tests, vital sign measurements and 12-lead electrocardiogram (ECG).

Exclusion Criteria

1. Presence or history of any disorder that may prevent the successful completion of the study.
2. Any history or presence of chronic respiratory disorder or disease including but not limited to asthma, sleep apnea, or chronic obstructive pulmonary disease (COPD).