Biomarker potential of heme oxygenase-1 in Alzheimer's disease and mild cognitive impairment.

The advent of an accessible chemical biological marker that differentiates early, sporadic Alzheimer's disease (AD) from normal aging and other dementing illnesses, and identifies individuals with mild cognitive impairment who are destined to deteriorate to Alzheimer's dementia, would represent a major achievement in the evaluation and management of this common neurodegenerative disorder. Although several candidate biomarkers of sporadic AD have been identified and commercialized, none currently fulfill the criteria for an ideal test. In this article, we review evidence implicating blood heme oxygenase-1 mRNA/protein levels and a recently identified plasma heme oxygenase-1 suppressor factor as potential biomarkers of AD and mild cognitive impairment.