Lipid peroxidation is a major outcome of free radical-mediated injury to brain, where it directly damages membranes and generates a number of oxidized products.

Some of the chemically and metabolically stable oxidation products are useful in vivo biomarkers of lipid peroxidation. These include the isoprostanes (IsoPs) and isofurans (IsoFs), derived from arachidonic acid (AA), and neuroprostanes (NeuroPs), derived from docosahexaenoic acid (DHA).

We have shown increased levels of IsoPs, NeuroPs, and IsoFs in diseased regions of brain from patients who died from advanced Alzheimer's disease (AD) or Parkinson's disease (PD). Increased cerebrospinal fluid (CSF) levels of IsoPs are present in patients with AD or Huntington's disease (HD) early in the course of their illness, and CSF IsoPs may improve the laboratory diagnostic accuracy for AD. In contrast, quantification of IsoPs in plasma and urine of AD patients has yielded inconsistent results. These results indicate that brain lipid peroxidation is a potential therapeutic target early in the course of AD and HD, that CSF IsoPs may aid in the assessment of anti-oxidant experimental therapeutics and laboratory diagnosis of AD.