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Wednesday, 12 June, 2002, 23:13 GMT 00:13 UK
Alzheimer's brains 'like dying batteries'
The finding could offer hope of a treatment for Alzheimer's
The finding could offer hope of a treatment for Alzheimer's
Scientists say the brains of Alzheimer's patients are like dying batteries, losing the power to retain memories.

The team from America which made the comparison says it could point to a new way in which Alzheimer's damages the brain, and the possibility of one day developing new drugs to treat the condition.

But UK experts have urged caution.


The mechanism they have discovered has only been demonstrated in a test tube

Dr Richard Harvey, Alzheimer's Society
The US scientists' theory is that as the disease affects nerve cells in the brain, electrical charges leak out taking memories with them.

The finding has yet to be demonstrated in living animals, but if it is, the team suggests drugs that prevent the electrical leakage could be developed to treat Alzheimer's.

Nerve cells operate like tiny batteries.

There is an electrical charge between the outside and the inside of the cell which allow them to receive and transmit electrical signals down the nerve.

This charge is called polarisation.

In Alzheimer's, a protein called beta amyloid peptide clumps together and forms plaques in the brain.

Chemical balance

Researchers from the Massachusetts Institute of Technology looked at nerve cells in a test tube and found when they were touched by plaques, channels on the cell surface open up to let in a flood of calcium ions.

This upsets the chemical balance of the cell and it dies.

But the researchers also found that when a plaque touches the cells, negative chloride ions flow out, draining the cell of its negative charge, like a battery going dead.

The team monitored the flow of ions across cell membranes by adding special dyes to cultures of human and rat nerve cells.

When the amyloid peptide was added, the cells soon became depolarised.


Research such as this takes our understanding of the basic mechanisms of Alzheimer's disease one step forward

Dr Richard Harvey
Alzheimer's Society
If this happened in a memory-forming cell, the memory would be lost.

The cells were then exposed to 1,500 different types of drugs. Ten reversed the depolarisation.

The team hope to carry out further research using mice.

Vernon Ingram, who led the research, said: "So far, we've only shown this in cell cultures.

"But it's a very promising first step and we're very excited about this."

Dr Richard Harvey, director of research at the Alzheimer's Society, said the discovery that some drugs could interfere with the mechanisms of the disease at a cellular level offered avenues for further study.

'Toxic'

"Research such as this takes our understanding of the basic mechanisms of Alzheimer's disease one step forward."

But he added: "The main issue here is that the mechanism they have discovered has only been demonstrated in a test tube - in real life, the human brain, which is vastly more complex than a single cell in a test tube, depolarisation may not be very important.

"Similarly, the drugs may be too toxic, may not have any effect on depolarisation in a living person, or even more simply, blocking depolarisation may have no effect on Alzheimer's disease in humans."

The research is published in New Scientist magazine and Biochemical and Biophysical Research Communications.

See also:

15 May 02 | Health
20 Dec 00 | A-B
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