Copper, ceruloplasmin and superoxide dismutase (SOD1) in patients with Down's syndrome

The aim of this study was primarily to investigate whether similar signs of copper dyshomeostasis occur in dementia with age in Down's syndrome as previously found in Alzheimer's disease. Copper was accordingly determined in plasma, ceruloplasmin concentration in serum, ceruloplasmin oxidative activity and ceruloplasmin specific oxidative activity (activity related to mass) in serum, and superoxide dismutase (SOD1) in erythrocytes in 35 (27 males, 8 females) 18-53 years old (average 37 years) patients with Down's syndrome (Down's patients) and their age- and gender-matched controls. SOD1 activity was on an average almost 50% higher in the patients than in their controls but the evidence of a causal relationship between increased SOD1 activity and Down's syndrome appears at best equivocal. Copper and ceruloplasmin levels and ceruloplasmin activities were similar in the patients and their controls. Ceruloplasmin and copper levels increased significantly with age in the patients but not in the controls. Ceruloplasmin activities or SOD1 activity did not change significantly with age, neither in the patients nor in the controls as whole groups. When SOD1 activity and ceruloplasmin activities of the oldest in the patients group (40 years or older) were compared with those of the younger patients, respectively, SOD1 activity and specific oxidative activity, but not ceruloplasmin oxidative activity were found to decrease significantly with age. The results thus suggest that development of dementia in Down's patients with age is paralleled with decrease in SOD1 activity and specific oxidative activity but not with decrease in ceruloplasmin oxidative activity itself as was also found in Alzheimer's patients.