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Calcium May Be Link to
Alzheimer’s
By Rick Nauert, Ph.D.
Researchers have shown that
mutations in two proteins associated with familial Alzheimer’s
disease disrupt the flow of calcium ions within neurons.
Alzheimer’s disease affects as many
as 5 million Americans, 5 percent of whom have the familial form.
The hallmark of the disease is the accumulation of tangles and
plaques of amyloid beta protein in the brain.
“The amyloid hypothesis has long
been invoked to explain the cause of Alzheimer’s” says lead author
J. Kevin Foskett, PhD, Professor of Physiology at the University of
Pennsylvania School of Medicine.
In the new study, published in the
journal Neuron, cells that carried a mutated gene or protein called
PS1 showed increased processing of amyloid beta.
This observation links mis-regulation
of calcium inside cells with the production of amyloid, a
characteristic feature in the brains of people with Alzheimer’s
disease.
“The ‘calcium dysregulation’
hypothesis for inherited, early onset familial Alzheimer’s disease
has been suggested by previous research findings, but our current
study identifies a molecular mechanism that makes this hypothesis
very compelling,” says Foskett.
Current therapies for Alzheimer’s
include drugs that treat the symptoms of cognitive loss and
dementia. Drugs that address the pathology of Alzheimer’s are only
experimental.
For example, a vaccine that
stimulates antibodies to amyloid beta is currently being
investigated. But these new observations suggest that new approaches
could be explored.
“The significance of identifying
the molecular mechanism and pathway of disrupted calcium signaling
is that a number of novel treatment targets can now be developed and
tested,” says Foskett.
The central role of calcium
signaling disruptions in Alzheimer’s is strengthened by another
study in which the Foskett laboratory was involved. This research
was published in the June 27 issue of Cell.
“Calcium is the common denominator
in our two studies, strongly suggesting that it plays an important
role in the development of Alzheimer’s disease,” notes Foskett.
“However, our experiments have
identified calcium inside cells as the important feature. No one
should consider modifying their dietary intake of calcium as a
strategy to limit the risk of developing Alzheimer’s disease,
because the body very effectively regulates the amount of calcium
absorbed from food and the levels in the blood and brain.
“And it is also very important for
people who take calcium channel blockers, for cardiovascular
problems for example, not to alter their medication regime as a
response to our studies.”
This research was supported by
grants from the National Institutes of Health and the Alzheimer’s
Disease Core Center at Penn. --
PsychCentral.com
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