Increased levels of magnetic iron compounds in Alzheimer's disease.

A study of the magnetic properties of superior temporal gyrus brain tissue from 11 Alzheimer's disease (AD) and 11 age-matched control subjects demonstrates an exponential correlation between the concentrations of the Fe;{2+}-ion-containing iron oxide, magnetite (Fe{3}O{4}), and the fraction of those particles that are smaller than 20 nm in diameter. These data provide circumstantial evidence in favor of their genesis within the 8 nm diameter cores of the iron storage protein ferritin. We also show, for the first time, that the total concentration of biogenic magnetite is generally higher in the AD brain (in some cases as much as 15 times greater than controls) and that there are gender-based differences, with AD female subjects having significantly higher concentrations than all other groups. These results provide insights which may guide current efforts to develop iron-based MRI diagnosis of AD.