A novel view of the mechanisms of neurodegeneration: "o one knows the cause of most cases of Alzheimer's, Parkinson's and other neurodegenerative disorders. But researchers have found that certain factors are consistently associated with these debilitating conditions. One is DNA damage by reactive oxygen species, highly destructive molecules usually formed as a byproduct of cellular respiration. Another is the presence of excessive levels of copper and iron in regions of the brain associated with the particular disorder. ... A high level of copper or iron, they say, can function as a 'double whammy' in the brain by both helping generate large numbers of the DNA-attacking reactive oxygen species and interfering with the machinery of DNA repair that prevents the deleterious consequences of genome damage. ... We don't yet know enough about all the biochemical mechanisms involved, but we have found multiple toxic mechanisms linking elevated iron and copper levels in the brain and extensive DNA damage - pathological features associated with most neurodegenerative disorders. ... some people's tissues contain much larger quantities of iron or copper, which overwhelm the proteins that normally bind the metals and sequester them for safe storage. The result: so-called 'free' iron or copper ions, circulating in the blood and able to initiate chemical reactions that produce reactive oxygen species. Reactive oxygen species cause the majority of the brain cell DNA damage that we see in Alzheimer's and Parkinson's disease, as well as most other neurodegenerative disorders."