title: Peripheral oxidative stress biomarkers in mild cognitive impairment and Alzheimer's disease.
abstract: Oxidative stress has been associated with normal aging and Alzheimer's disease (AD). However, little is known about oxidative stress in mild cognitive impairment (MCI) patients who present a high risk for developing AD. The aim of this study was to investigate plasma production of the lipid peroxidation marker, malonaldehyde (MDA) and to determine, in erythrocytes, the enzymatic antioxidant activity of catalase, glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione S-transferase (GST) in 33 individuals with MCI, 29 with mild probable AD and 26 healthy aged subjects. GR/GPx activity ratio was calculated to better assess antioxidant defenses. The relationship between oxidative stress and cognitive performance was also evaluated by the Mini Mental State Examination (MMSE). AD patients showed higher MDA levels than both MCI and healthy elderly subjects. MCI subjects also exhibited higher MDA levels compared to controls. Catalase and GPx activity were similar in MCI and healthy individuals but higher in AD. GR activity was lower in MCI and AD patients than in healthy aged subjects. Additionally, GR/GPx ratio was higher in healthy aged subjects, intermediate in MCI and lower in AD patients. No differences in GST activity were detected among the groups. MMSE was negatively associated with MDA levels (r = -0.31, p = 0.028) and positively correlated with GR/GPx ratio in AD patients (r = 0.68, p < 0.001). MDA levels were also negatively correlated to GR/GPx ratio (r = -0.31, p = 0.029) in the AD group. These results suggest that high lipid peroxidation and decreased antioxidant defenses may be present early in cognitive disorders.
authors: Department of Clinical Chemistry and Toxicology, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil.
authors: Larissa Lobo
authors: LL
authors: Torres
authors: Nathalia Barbosa
authors: NB
authors: Quaglio
authors: Gisele Tavares
authors: GT
authors: de Souza
authors: Raphael Tamborelli
authors: RT
authors: Garcia
authors: Lívia Mendonça Munhoz
authors: LM
authors: Dati
authors: Wallace Luiz
authors: WL
authors: Moreira
authors: Ana Paula de Melo
authors: AP
authors: Loureiro
authors: Juliana Nery
authors: JN
authors: de Souza-Talarico
authors: Jerusa
authors: J
authors: Smid
authors: Cláudia Selito
authors: CS
authors: Porto
authors: Cássio Machado de Campos
authors: CM
authors: Bottino
authors: Ricardo
authors: R
authors: Nitrini
authors: Silvia Berlanga de Moraes
authors: SB
authors: Barros
authors: Rosana
authors: R
authors: Camarini
authors: Tania
authors: T
authors: Marcourakis