Pubdate: 9 Nov 1998
Source: Daily Telegraph (Australia)
Contact:  Roger Highfield, Science Editor 

NICOTINE-LIKE DRUGS MAY SLOW ALZHEIMER'S

INSPIRED by how smoking can help combat the effects of Alzheimer's disease,
scientists have developed nicotine-like compounds to separate this
beneficial effect from the hazards of tobacco.

These compounds can help to restore the ability to learn and remember in
rats that have brain lesions similar to those in Alzheimer's disease
patients, scientists were told yesterday.

Dr Edward Levin, of Duke University Medical Centre, North Carolina, told
the Society of Neuroscience annual meeting in Los Angeles that rats given a
drug called AR-R 17779 performed significantly better than untreated rats
on standard learning and memory tests. The compound was developed by Astra
Arcus USA, a pharmaceutical company based in Worcester, Massachusetts,
which also supported the research study.

AR-R 17779 is one of a new class of drugs aimed at combating the learning
and memory deficits associated with Alzheimer's disease. These compounds
work by docking to specific sites on the surface of brain cells called
acetylcholine receptors. Nicotine or a nicotine look-alike can activate
these receptors, which enhance the brain's ability to learn and remember.
Some studies suggest that nicotinic receptor stimulation, especially
activation of a specific nicotinic receptor sub-type that AR-R 17779 binds
to, may be able to protect brain cells from deterioration caused by
Alzheimer's disease.

Dr Levin and his colleagues tested the ability of AR-R 17779 to boost
learning and memory in rats placed on a standard radial arm maze test, a
structure consisting of a platform with planks radiating from it. At the
end of each plank is a food reward. Once eaten, the food is not replaced.
Normal rats quickly learn that it is not worth going down the same plank
twice, whereas rats with the brain lesions show significantly slower
learning and memory.

Dr Levin said: "When we injected the impaired rats with the compound 20
minutes before testing, the animals showed significantly improved learning
and even a reversal of the working memory impairment normally seen in these
animals. However, further testing will certainly be required to confirm and
expand on these results."

Dr Levin also is conducting clinical trials using nicotine skin patches to
try to improve attention and memory in Alzheimer's disease patients. He
said: "We know that nicotine or nicotine-like drugs may not be a cure-all
for Alzheimer's disease. But if we could prolong the period of time that
patients can be independent and functional, it could mean a much better
quality of life for them and their care givers."

The results of the human studies are expected in 1999. Dr Levin said: "We
would certainly discourage the use of nicotine products or taking up
smoking for Alzheimer's disease patients. Our goal is to find a
nicotine-like substance that will give the beneficial effects of nicotine
without the harmful side effects or addictive ability." 
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Checked-by: Mike Gogulski