Research uncovers vital corner piece of the jigsaw puzzle.
Australian scientists have made a significant advance in the understanding of Alzheimer's disease, a condition they describe as an accumulation of brain "rust".
An imbalance in the metals needed for healthy brain function has been found at the root of the degenerative disease which afflicts 10 per cent of people aged over 60.
University of Melbourne professor of pathology Ashley Bush and his research colleagues have traced the imbalance to the brain's improper and related processing of zinc and iron.
Their research is detailed in a paper to be published in the international journal Cell later this month.
"The brain in Alzheimer's disease is a catastrophe, and it is very hard to pinpoint what went wrong first," Bush said.
"This (research) really unravels quite a big series of knots and highlights a particular sequence involving these two metals.
"... It is the most in-depth series of biochemical discoveries about Alzheimer's disease and its causes to date."
The research focused on the complex relationship between amyloid precursor protein (APP) and its breakdown product amyloid, along with the zinc and iron.
Bush said as zinc was seen to accumulate in amyloid it blocked the APP from performing its critical, and previously unknown, job of exporting iron out of the brain's neurons.
This led to a build-up of iron "in the grey matter", he said, resulting in oxidative stresses that could kill off neurons.
So could you say the loss of mental function in an Alzheimer's patient is caused by rust in their brain?
"In a chemical sense, you can," Bush said.
"That's the kind of chemistry that is going on in the brain and, similar to actual rust, it involves an abnormal combustion of oxygen with iron.
"The brain is an unusual organ in that it has very high concentrations of metals which it uses for its electrical chemistry."
While the research does not reveal the complete picture of the cause of Alzheimer's disease, Bush said it had uncovered a vital "corner piece of the jigsaw puzzle".
Revealing more of the factors contributing to Alzheimer's disease hands the scientific community a broader target, as they work to develop treatments that could halt the damage.
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