- Patient who have a history or presence of clinically relevant CNS pathology such as epilepsy, seizure, paresis, aphasia, stroke, severe brain injuries, dementia, Parkinson's disease, cerebellar disease, psychosis, or other significant CNS abnormalities. A history of treated CNS leukemia or lymphoma will be allowed if recent imaging and CSF studies confirm the absence of active CNS disease at the time of study entry