7. Subjects have evidence of any chronic organic diseases of the CNS (other than schizophrenia), such as tumors related to the CNS, inflammation related to the CNS, active seizure disorder, vascular disorder, Parkinson's disease, Alzheimer's disease, or other forms of dementia, myasthenia gravis, or other degenerative processes. Subjects have a medical history of mental retardation or persistent neurological symptoms resulting from serious head injury.