CLINICAL SCIENCES Malondialdehyde, Superoxide Dismutase, Melatonin, Iron, Copper, and Zinc Blood Concentrations in Patients with Alzheimer Disease: Cross-sectional Study

Aim. To investigate the oxidative stress hypothesis in patients with Alzheimer type dementia. Method. Serum melatonin, Zn, Cu, Fe, and malondialdehyde (MDA) concentrations and erythrocyte superoxide dismutase (SOD) activity were measured in patients with Alzheimer disease. Mini-Mental State Examination (MMSE) scores were obtained for the patients and their ageand sex-matched healthy controls. Results. MMSE score was 16.8±1.3 in patients with Alzheimer disease, and 28.2±2.4 in control group. Melatonin levels were lower in the Alzheimer disease group (170.5±5.2 pg/mL) than in the control group (205.2±5.8 pg/mL) (p<0.001). Fe, SOD, and MDA levels were higher in Alzheimer disease group (131.7±4.8 μg/dL, 1,510±90 U/g Hb, and 38.1±4.7 nmol/mL; respectively) than in the control group (97.1±4.1 μg/dL, 1,120±50 U/g Hb, and 17.2±1.6 nmol/mL; respectively) (p<0.001 for all comparisons). A statistically significant negative correlation between melatonin and SOD (r=-0.421, p=0.014) and a positive correlation between age and Fe (r=0.325, p=0.049) were found only in the Alzheimer disease group. Correlation between age and melatonin was positive (r=0.481, p=0.006) in Alzheimer disease group and negative (r=-0.472, p=0.009) in the control group. Conclusion. Melatonin blood concentration was significantly decreased, and Fe and MDA levels were increased in the patients with Alzheimer disease. We believe that low level of melatonin, especially if there is a simultaneous increase in Fe level, is associated with the development of Alzheimer disease.