“…Antioxidant defense status changes accordingly (Herken et al, 2001a;Yao et al, 1998a). Superoxide dismutase (SOD), a key enzyme involved in the detoxification of superoxide radicals, has been consistently found increased (Vaiva et al, 1994;Yao et al, 1998b;Zhang et al, 2003a) in drug-free patients or those with TD (tardive dyskinesia) (Yao et al, 1998b;Zhang et al, 2003a), unchanged (Herken et al, 2001a) or decreased (Zhang et al, 2006) (Yao et al, 1998b) while unchanged (Yao et al, 1999) or decreased (Zhang et al, 2006) in chronic patients. Other antioxidant enzyme activity such as catalase (CAT) increased (Herken et al, 2001a) in different form of schizophrenia.…”