Plasma oxidative stress parameters in men and women with early stage Alzheimer type dementia.

It is well known that oxidative stress is one of the earliest events in Alzheimer's disease pathogenesis, indicating that may play a key role in this disease. In our study, we measured the levels of oxidative stress indicators (TBARS and protein carbonyls content) and the non-enzymatic (glutathione (GSH) and oxidized glutathione (GSSG)) and enzymatic (glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD)) defense systems in the plasma of 46 patients diagnosed of ATD and 46 age-matched controls. We found decreased levels in total GSH in ATD patients, although healthy control women showed lower levels of total GSH than healthy control men. On the contrary, we found increased levels of TBARS and carbonyl groups content in ATD patients in both genders. The activity of the plasma antioxidant enzymes showed no changes for SOD activity in ATD patients, independently of the gender, although western blot analysis showed an increase in SOD-1 protein. CAT activity was also decreased in ATD patients, although this decrease is mainly due to the decrease found in men but not in women. However, western blot analysis did not show differences in CAT protein between controls and ATD patients. Finally, a decrease of GPx activity was found in ATD patients in both genders. However, as with CAT protein, western blot analysis did not show differences in GPx protein between controls and ATD patients. Our results suggest that there is a defect in the antioxidant defense system that is incapable of responding to increased free radical production, which may lead to oxidative damage and the development of the pathological alterations that characterize the neurodegenerative disorder of patients with ATD. Thus, oxidative damage could be one important aspect for the onset of ATD and oxidative stress markers could be useful to diagnose the illness in their earliest stages through both non-invasive, reliable and cost-affordable methods.