Evidence of any chronic organic disease of the CNS such as tumors, inflammation, active seizure disorder, vascular disorder, potential CNS related disorders that might occur in childhood- eg, Duchenne Muscular dystrophy, myasthenia gravis, or other neurologic or serious neuromuscular disorders. In addition, subjects must not have a history of persistent neurological symptoms attributable to serious head injury. Past history of febrile seizure, drug-induced seizure, or alcohol withdrawal seizure is not exclusionary.