Copper
linked to Alzheimer's disease
By James GallagherHealth and science reporter, BBC News
Mixed evidence on the role of copper in Alzheimer's
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A lifetime of too much copper in our diets may be
contributing to Alzheimer's disease, US scientists say.
However, research is divided, with other studies
suggesting copper may actually protect the brain.
The latest study in Proceedings of the National Academy of Sciences showed high levels of copper left the brain struggling to get rid
of a protein thought to cause the dementia.
Copper is a vital part of our diet and necessary
for a healthy body.
Tap water coming through copper pipes, red meat and
shellfish as well as fruit and vegetables are all sources of dietary copper.
Barrier
The study on mice, by a team at the University of
Rochester in New York, suggested that copper interfered with the brain's
shielding - the blood brain barrier.
Mice that were fed more copper in their water had a
greater build-up of the metal in the blood vessels in the brain.
The team said this interfered with the way the
barrier functioned and made it harder for the brain to get rid of a protein
called beta amyloid.
One of the hallmarks of Alzheimer's disease is the
formation of plaques of amyloid in the dying brain.
Lead researcher Dr Rashid Deane said: "It is
clear that, over time, copper's cumulative effect is to impair the systems by
which amyloid beta is removed from the brain."
He told the BBC that copper also led to more
protein being produced: "It's a double whammy of increased production and
decreased clearance of amyloid protein.
"Copper is a very essential metal ion and you
don't want a deficiency and many nutritious foods also contain copper."
However, he said taking supplements may be
"going overboard a bit".
Mixed evidence
Commenting on the latest findings, Chris Exley,
professor of bioinorganic chemistry at Keele University, said there was
"no true consensus" on the role of copper in Alzheimer's disease.
His research on human brains reached the opposite conclusion: "In our most recent work we
found evidence of lower total brain copper with ageing and Alzheimer's. We also
found that lower brain copper correlated with higher deposition of beta amyloid
in brain tissue.
"He said at the moment we would expect copper
to be protective and beneficial in neurodegeneration, not the instigator, but
we don't know.
"The exposure levels used mean that if copper
is acting in the way they think it does in this study then it must be doing so
in everyone."
Dr Eric Karran, from Alzheimer's Research UK, said:
"While the findings present clues to how copper could contribute to
features of Alzheimer's in mice, the results will need replicating in further
studies. It is too early to know how normal exposure to copper could be
influencing the development or progression of Alzheimer's in people. "
Dr Doug Brown, from the Alzheimer's Society, said:
"Considering copper is a vital mineral for the body, people should treat
these results with caution and not cut it out of their diet. More research is
needed to understand the role that copper might play in the brain."
