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Increased oxidative damage in nuclear and mitochondrial DNA in mild cognitive impairment

Jianquan Wang1, William R Markesbery, Mark A Lovell

  • 1Department of Chemistry, University of Kentucky, Lexington, KY 40536-0230, USA.

Journal of Neurochemistry
|January 13, 2006
PubMed

Insights

Oxidative damage to DNA occurs in mild cognitive impairment (MCI), an early stage of Alzheimer's disease (AD). This DNA oxidation in the brain suggests a role in the disease's development.

Area of Science:

  • Neuroscience
  • Biochemistry
  • Genetics

Background:

  • Oxidative damage is linked to aging and neurodegenerative diseases like Alzheimer's disease (AD).
  • Mild cognitive impairment (MCI) precedes dementia and AD, but the onset of DNA oxidation in MCI is not well understood.

Purpose of the Study:

  • To investigate whether DNA oxidation occurs in the brains of individuals with MCI.
  • To determine if oxidative damage is present in the early stages of Alzheimer's disease.

Main Methods:

  • Quantified oxidized bases in nuclear and mitochondrial DNA from brain regions of MCI patients and controls.
  • Utilized gas chromatography/mass spectrometry with selective ion monitoring for precise measurements.
  • Analyzed samples from short post-mortem interval autopsies.

Main Results:

  • Significantly elevated levels of 8-hydroxyguanine found in MCI nuclear DNA (frontal, temporal lobes) and mitochondrial DNA (temporal lobe).
  • Increased 8-hydroxyadenine and 4,6-diamino-5-formamidopyrimidine observed in MCI nuclear DNA across neocortical regions.
  • Elevated 4,6-diamino-5-formamidopyrimidine also detected in MCI mitochondrial DNA (temporal, frontal, parietal lobes).

Conclusions:

  • Oxidative damage to both nuclear and mitochondrial DNA is present in the earliest detectable phase of Alzheimer's disease (MCI).
  • These findings suggest that oxidative DNA damage plays a significant role in the pathogenesis of Alzheimer's disease.

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