PLAT and hyperhomocysteinemia: Conditions affecting the activity of tPA, such as hyperhomocysteinemia and antiphospholipid antibodies, have been consistently described in drug-naive schizophrenia.7, 8, 9, 10 We recently screened 70 drug-treated schizophrenia patients and 98 controls for these and other conditions affecting tPA activity.11 Persistent antiphospholipid antibodies were seen in 30% of the patients and none of the controls.