Early Intervention of Prodromal Schizophrenia Using an NMDA Enhancer

This study tests whether a drug that boosts a brain chemical (NMDA receptor enhancer) can reduce early warning signs of schizophrenia — a phase called "prodromal schizophrenia" or "clinical high risk" — and potentially prevent or delay the onset of full psychosis. **You may be eligible if...** - You have early or mild symptoms suggesting a risk of developing schizophrenia (attenuated psychotic symptoms, brief psychotic episodes, or a family history with recent functioning decline) - You remain symptomatic after a 6-week health support program - You are either not on psychiatric medication, or have been on stable doses for at least 4 weeks **You may NOT be eligible if...** - You have already experienced a full psychotic episode requiring hospitalization - You have serious physical health problems that interact with the study drug - You are pregnant or planning to become pregnant Talk to your doctor to see if this trial is right for you.