The aim of the proposed study is to investigate the efficacy and safety of add-on gamma-glutamylethylamide (L-theanine) versus a placebo for antipsychotic treatment for 8 weeks in a randomized, double-blind, parallel group study of 60 patients with schizophrenia and schizoaffective disorders.

This is a two-year randomized placebo-controlled double-blind investigation of the use of augmentative L-theanine in the management of 60 patients with schizophrenia and schizoaffective disorders. We will investigate several outcome variables in these patients including the positive and negative symptoms, affective features, emotional distress, neuropsychological testing, side effects, and the quality of life. Participating subjects on stable antipsychotic treatment will be randomized to receive for 8 weeks either L-theanine (400 mg/day) or a placebo in addition to regular ongoing antipsychotic medication for 8 weeks. Subjects will be assessed at baseline and after 2, 4, 6, and 8 weeks of treatment using psychiatric rating scales, self-reported questionnaires, and a neuropsychological battery of tests. The efficacy and safety of augmenting antipsychotic treatment with L-theanine will be analyzed.

The Cambridge Neuropsychological Test Automated Battery (CANTAB) will be administered at commencement and completion of the study. The CANTAB battery consists of a series of interrelated computerized tests of visual and movement skills, attention and memory, and executive function, administered via a touch sensitive screen. The nonverbal nature of the CANTAB tests makes them largely language independent and culture free. These tests are run on an IBM-compatible personal computer with a touch-sensitive screen. Neuropsychological testing lasts approximately 2 hours. Subjects complete the tests in a fixed order with a break half-way through the testing session. For a description of the nature of these tests, the performance measures used, and how the test scores are derived, see (http://www.cantab.com/cantab/site/home.acds). The neuropsychological tests are categorized onto five cognitive domains: visual and movement skills, attention, memory, learning, sustained attention, and executive function: Motor Screening, Big/Little Circle, Reaction Time, Matching to Sample Visual Search, Delayed Matching to Sample, Pattern Recognition Memory, Spatial Recognition Memory, Spatial Span, Rapid visual information processing, Spatial working memory, Intra/Extra Dimensional Set Shift, and Stockings of Cambridge. In addition to raw scores from these tasks, the average value of the z-scores of the CANTAB neurocognitive tasks will be used to determine cognitive indices in specific domains.

Inclusion Criteria:

• Age 18-60 years, men or women
• DSM-IV criteria for schizophrenia or schizoaffective disorder
• At least 4 on the Clinical Global Impression Scale
• At least two weeks of ongoing treatment with current antipsychotic agents.
• Ability and willingness to sign an informed consent form for participation in the study.

Exclusion Criteria:

• Evidence of serious neurologic or endocrine disorder, for example severe head trauma, seizure disorder, dementia, Cushings disease, or thyroid disorder, mental retardation, alcohol or drug abuse.
• Renal disease
• Hepatic dysfunction
• Pregnant women
• Patients receiving mood stabilizing medications.