Correlations of glutathione peroxidase activity with memory impairment in adults with Down syndrome

Background: Down syndrome (DS) is a genetic disorder (trisomy 21 in 96% of cases), associated with an excess of a key enzyme involved with free radica l metabolism (FRM), superoxide dismutase-1 (SOD-1), that is encoded by a ge ne on chromosome 21. Consequently, SOD-1 activity is elevated in DS, which also occurs in conditions of oxidative stress, and is associated with a com pensatory increase in glutathione peroxidase activity (GSHPx). Methods: This study examined the relationship of memory function with eryth rocyte SOD-I, GSHPx and catalase (CAT) activity in 22-51 year old adults wi th DS. Results: Mean erythrocyte SOD-1 (p < .02) and GSHPx (p < .01), but not CAT (p = .76), activities were significantly greater in the DS group than the c ontrols. In the DS group, erythrocyte GSHPx; but not SOD-I or CAT activitie s was significantly correlated with memory function (r = .625 p < .025 df = 13 for savings score, r = .631, p < .01, df = 14 for intrusion errors) but not with intelligence quotients. Conclusions: These observations suggest a possible relationship between alt ered FRM with memory deficits among adults with DS within the age-range in that an age-related increase in the prevalence for Alzheimer's neuropatholo gy is known to be robust before reaching a plateau of 100%. Biol Psychiatry 1999;46:1682-1689.