Evidence of increased oxidative damage in subjects with mild cognitive impairment

TLDR

To determine whether increased oxidative damage is present in the brains of persons with mild cognitive impairment, a condition that often precedes Alzheimer disease. The authors measured protein carbonyls, thiobarbituric acid‑reactive substances, and malondialdehyde in the superior and middle temporal gyri and cerebellum of postmortem samples from normal subjects, MCI patients, and early AD patients. The study found markedly higher protein carbonyls (~25 %), malondialdehyde (~60 %), and TBARS (~210 %) in the superior and middle temporal gyri of MCI and early AD patients versus controls, with TBARS associated with neuritic plaques and protein carbonyls correlating with poorer delayed verbal memory, indicating oxidative damage as an early event in Alzheimer disease.

Abstract

<b>Objective: </b> To determine if increased levels of oxidative damage are present in the brains of persons with mild cognitive impairment (MCI), a condition that often precedes Alzheimer disease (AD). <b>Methods: </b> The authors assessed the amount of protein carbonyls, thiobarbituric acid-reactive substances (TBARS), and malondialdehyde in the superior and middle temporal gyri (SMTG) and cerebellum of short postmortem interval and longitudinally evaluated normal subjects and those with MCI and early AD. <b>Results: </b> Elevated levels of protein carbonyls (∼25%), malondialdehyde (∼60%), and TBARS (∼210%) were observed in the SMTG of individuals with MCI and early AD vs normal control subjects. The elevation in TBARS was associated with the numbers of neuritic but not diffuse plaques. Levels of protein carbonyls increased as delayed verbal memory performance declined. <b>Conclusion: </b> Oxidative damage occurs in the brain of subjects with mild cognitive impairment, suggesting that oxidative damage may be one of the earliest events in the onset and progression of Alzheimer disease.