2 Week, Lead-in Evaluation Phase: In the 2 week lead-in evaluation phase, subjects will receive placebo. They will undergo baseline symptom, medical, safety, and neurocognitive assessments. The subjects will undergo a physical examination; including neurological exam, an EKG; and laboratory tests of major organ functions (i.e., CBC (complete blood count), liver function tests, electrolytes, glucose, BUN/Creatinine, Urinalysis (UA), urine toxicology, and thyroid functions). Baseline antipsychotic levels will be collected. All women will have a pregnancy test, unless they are either surgically or hormonally post menopausal.