RESUMO
OBJECTIVES: To evaluate the differences concerning cognitive performance, oxidative stress and vitamin B12 levels in omeprazole users under treatment for longer than six months. METHODS: A case-control study was developed with 44 omeprazole users (OU; 81.8 % female, 66 ± 8.7 years old) and 35 nonusers (NOU; 88.6 % female, 62 ± 8.7 years old). The cognitive ability was assessed through tests approaching attention, memory and executive functions. The vitamin B12 was dosage using a chemiluminescent immunoassay and oxidative stress analysis, based on the evaluation of malondialdehyde, enzymatic activity of extracellular superoxide dismutase, glutathione peroxidase, catalase and the ferric reducing antioxidant power in plasma. KEY FINDINGS: A significant increase of the ferric reducing antioxidant power [omeprazole users (OU) group = 1690 µM ± 441 and nonusers (NOU) group = 1308 ± 616; P value=0.002] and a decrease on glutathione peroxidase levels [OU group = 0.534 (0.27-10.63) and NOU group = 71.86 (14.36-173.1); P value=0.006] were found on omeprazole users group, as well as differences on cognitive performance, with impairments on executive functions, automatic and attentional processing. CONCLUSIONS: Long-term use of omeprazole is suggested to induce an oxidative stress condition, which causes neurotoxicity and cognitive decline.