Erythrocyte superoxide dismutase activity differs in clinical subgroups of Parkinson's disease patients

There is controversy as to whether there are clinical subgroups in Parkinson's disease (PD). Six tremor-dominant and six bradykinesia-dominant patients identified among 29 cases with PD were compared in terms of erythrocyte superoxide dismutase (SOD) activity and several clinical variables. Erythrocyte SOD activity in tremor-dominant patients was higher than in bradykinesia-dominant patients. According to our preliminary results obtained from small number of patients, the difference of SOD activity in clinically distinct subgroups suggests there may be separate clinical subgroups of PD which can be differentiated by a biological marker.