BACKGROUND Tardive dyskinesia (TD) may be mediated through free radical damage to neurons. Plasma lipid peroxide levels are a measure of radical damage to fats. Vitamin E is a free radical scavenger.
METHOD One hundred and twenty-eight schizophrenic patients were examined for TD using the Abnormal Involuntary Movements Scale. Blood samples were taken to measure plasma lipid peroxide, serum vitamin E and cholesterol, and vitamin E:cholesterol ratios. Twenty-four patients were also examined in October 1993, January 1994, and April 1994. Biochemical results were compared in 81 patients and 79 normal subjects.
RESULTS Patients with and without TD did not differ in median plasma lipid peroxide and serum vitamin E levels, or vitamin E:cholesterol ratios. Correlations between seasonal change scores in TD and biochemical measurements were low. Lipid peroxide levels were higher and vitamin E:cholesterol ratios lower in patients than in normal subjects. Vitamin E levels were lowest in in-patients and in those living in supported accommodation.
CONCLUSIONS The results do not support the hypothesis that TD is mediated through free radical damage to neurons, but suggest increased free radical activity in schizophrenia.