TEN CHRONIC schizophrenic patients and nine nonschizophrenic control subjects were given d,l-methionine-d, l-sulfoximine (MSO) orally. A tenth nonschizophrenic subject was given a placebo. The ten schizophrenic patients, all from the Tulane Research Unit of the East Louisiana State Hospital, have been previously described.1 None had received shock treatment for at least three years or any medication for at least six months. The ten control subjects were volunteers from the Louisiana State Penitentiary, with no personal or family history of mental illness; all had been carefully screened by two psychiatrists for evidence of schizotypal adaptation (subclinical or pseudoneurotic schizophrenia) before final acceptance for the study.
In the interest of establishing maximal controls and maintaining efficient collection and processing of data, the study was divided into three parts. Certain procedures were common to all parts: collection of psychiatric data (including history and examination of mental