Antioxidant Capacity is Decreased in Alzheimer’s Disease and Mild Cognitive Impairment Patients

We investigated through measurements in serum, the occurrence of oxidative stress in patients with Alzheimer’s disease (AD), mild cognitive impairment (MCI) and healthy elderly controls. Possible correlations between a genetic risk factor for AD, the allele e4 of the apolipoprotein E (APOE) gene, and oxidative stress were also investigated. Through Thiobarbituric Acid Reactive Substances (TBARS) assay serum lipid peroxidation products of AD patients, MCI patients and controls were measured. We also analyzed the participants’ serum antioxidant status through 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye reduction. No difference between the groups was observed concerning TBARS levels (p = 0.212). Controls had a higher antioxidant status compared to AD (controls: 0.43 ± 0.061 O.D; AD: 0.39 ± 0.065 O.D), p = 0.002, and MCI patients (0.381 ± 0.065 O.D), p = 0.001. No difference concerning antioxidant status or TBARS levels was associated with the e4 APOE allele. Oxidative stress in MCI and AD patients seems to be evidenced in serum by a reduction of the antioxidant system capacity rather than change in the TBARS levels. MTT assay for evaluation of antioxidant status could be helpful in therapeutic intervention and guide changes in the life-style of individuals in early stages of cognition impairment.