- Males or females who are one year post-menopausal or without childbearing potential
- Between the ages of 50 and 85 years old
- Mild cognitive impairment confirmed by Mini Mental State Examination (MMSE) score between 23 and 27
- Cooperative, able to ingest oral medication, and able to complete all aspects of the study and capable of doing so, either alone or with the aid of a responsible caregiver, according to the investigator's judgement
- A current diagnosis of cerebrovascular disease, any primary neurodegenerative disorder, or any other causes of neuropsychologic disturbances or secondary dementia
- A current diagnosis of epilepsy or depression, or any other diagnosis that may interfere with the patient's response to study medication
- An advanced, severe or unstable disease of any type that may interfere with efficacy evaluations
Other protocol-defined exclusion criteria may apply.