There is a growing body of evidence that iron in the brain may play a role in Alzheimer’s disease. Lending weight to that idea, a new imaging probe has for the first time shown that in the same regions of the brain where the amyloid beta plaques associated with Alzheimer’s occur, there is also an increase in iron redox, meaning the iron in these regions is more reactive in the presence of oxygen. Their imaging probe could yield even more details about the causes of Alzheimer’s and help in the search for new drugs to treat it.