Inclusion Criteria:

• Age 18-60
• Able to provide informed, written consent
• Treatment for schizophrenia or schizoaffective disorder for 5 or more years
• Diagnosis of schizophrenia or schizoaffective disorder
• Psychiatrically stable as evidenced by no hospitalizations and no changes in psychiatric medications (with the exception of dosage adjustments and the prescription of adjunctive treatments for sleep disturbance or anxiety) within the prior 3 months, and as confirmed by clinical interview during the screening phase
• Total score > 60 baseline on The Positive and Negative Syndrome Scale (PANSS)
• Score > 3 on at least one of the five subscales of the SANS
• Non-Kraepelinian schizophrenia, as defined by the ability to independently provide for at least one domain of basic needs
• Females must be of non-child bearing potential or on appropriate contraceptive and not breast-feeding
• Females must have a negative serum beta HCG at screening
• Clinical laboratory values within normal limits, as defined in study protocol, or abnormalities considered not clinically significant by the investigator

Exclusion Criteria:

• Kraepelinian schizophrenia, as defined by dependency on others for the provision of all basic needs (including shopping, food preparation, household chores, and transportation);
• DSM-IV criteria for substance dependence (excluding nicotine and caffeine), as determined by SCID and chart review, during the 90 days prior to screening;
• Patients judged by the investigator as being at significant risk of suicide, violent behavior, or homicide;
• Concurrent participation or participation within the prior 30 days in any study involving investigational medications;
• Females who are pregnant or lactating;
• Neurodegenerative disorders such as Alzheimer's disease and other dementias, Parkinson's disease, Pick's disease, and Huntington's chorea;
• A history of significant cerebrovascular event yielding a physical or neurological deficit likely to confound the assessment of the subject's functioning;
• A history of significant head trauma, defined as head trauma resulting in neurological or cognitive sequelae;
• A known personal history of seizure disorder;
• A known sensitivity to cholinesterase inhibitors, choline agonists, or similar agents;
• Patients who are known to be HIV positive;
• Evidence of clinically significant, active gastrointestinal, hepatic, pulmonary, endocrine, renal, or cardiovascular system disease;
• Active or clinically significant conditions affecting absorption, distribution or metabolism of the study medication (e.g. inflammatory bowel disease or gastric or duodenal ulcers);
• Clinically significant urinary outflow obstruction;
• Patients with untreated thyroid disease;
• Patients with Type I or Type II diabetes controlled by medication or diet who do not have a HbA1c of < 8.5%;
• Patients with known significant cardiac history such as myocardial infarction or abnormal cardiac catheterization within the last 12 months.
• Unstable angina: angina or coronary artery disease requiring a change in medications within the 3 months prior to screening;
• Decompensated congestive heart failure;
• Severe mitral or aortic valvular disease;
• Atrial fibrillation;
• Greater than first degree atrioventricular block;
• QTc prolongation at screening;
• Bradycardia <50 beats/min;
• Current treatment with clozapine, olanzapine, chlorpromazine, or thioridazine;
• Use of potent cytochrome P450 inhibitors or inducers within 14 days before the Baseline Visit or during treatment, as listed in Appendix B of protocol;
• Current use of potent anticholinergic medication, as listed in Appendix B;
• Current use of any disallowed concomitant medication, as listed in Appendix B; and
• Any clinical finding that in the opinion of the investigator could potentially be negatively affected by study participation or that could potentially affect study participation is criterion for exclusion from the study.