Scientists know that the drug ketamine — street name “Special K” — can induce schizophrenia-like symptoms in drug abusers. Ketamine is also used as an anesthetic and, more recently, as an antidepressant — raising concerns by researchers at the UCSD School of Medicine, who have found that ketamine leads to the impairments in brain circuitry observed in both drug abusers and schizophrenic patients by causing increased production of a toxic free radical called “superoxide.”