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Removing aluminium from the brains of people with Alzheimer’s disease
can slow the rate of mental deterioration by 50 per cent. Donald McLachlan
and Theo Kruck, from the University of Toronto, told a conference of the
Ontario Health Ministry that injections of the drug desferrioxamine, which
‘mops up’ the metal, can prevent aluminium from doing irreversible damage
to brain cells. The finding greatly strengthens the evidence that aluminium
does play a part in Alzheimer’s disease, say the researchers.

The role of aluminium in Alzheimer’s is the subject of fierce debate
(see This Week, 21 July 1990). Autopsies have shown that the brains of Alzheimer’s
patients contain significantly more aluminium than those of other patients.
But some researchers argue that the presence of the metal in the cores of
the senile plaques that characterise the disease is incidental. Epidemiological
studies from Britain and France showed a slightly increased incidence of
Alzheimer’s disease in communities with high concentrations of aluminium
in their drinking water.

McLachlan and Kruck divided 48 Alzheimer’s patients into two groups.
One group remained untreated, while the others received injections of desferrioxamine,
a drug that binds to aluminium.

After two years, the results were significant, says Kruck. The untreated
group deteriorated about 50 per cent faster, to the extent that some of
them had to be admitted to nursing homes and several died. The patients
treated with desferrioxamine were still able to live in their own homes
with relatives or other carers looking after them. The patients were assessed
on a scale of quality of life, taking into account their ability to look
after themselves and to communicate with others.

McLachlan and Kruck believe that while aluminium is an essential factor
in the disease, there are other contributors, possibly a genetic or an immunological
component. These might damage the brain cell in some way, making it susceptible
to aluminium, or impair the body’s ability to keep the metal out of the
brain.

For example, one British team has found that people with Alzheimer’s
have a defective form of a common protein, transferrin, which binds aluminium
in the blood and prevents it from entering the brain (see New Å®ÉúСÊÓƵ,
Science, 7 April 1990). Transferrin in the blood of Alzheimer’s patients
is much less effective at binding the metal than it is in other patients.
This may mean that more aluminium is free to enter the brain, says Paul
Altmann, a member of the team from the Royal London Hospital.

‘The suggestion that aluminium is the cause of Alzheimer’s is made that
much stronger by these results,’ said Altmann. ‘The findings also fit very
well with the work we’ve done on transferrin.’

Once aluminium reaches the brain, one of its targets is the nucleus
of the nerve cells, where it interferes with the DNA and makes the DNA code
illegible. ‘The aluminium acts like crazy glue in the pages of a book,’
says Kruck. ‘When the DNA book cannot be read, the cells die.’

Desferrioxamine is commonly used to treat iron poisoning. It is poisonous
to nerve cells and can produce severe side effects, including nausea, anorexia,
deafness and blindness. In this study, the researchers prescribed the smallest
amount they felt would produce a response, giving only one-twentieth of
the dose recommended for iron poisoning. Now the question remains, would
a slighly higher dose retard the development of Alzheimer’s even more? And
would continued use of the drug hold back the course of the disease? These
questions and others will have to wait to be answered. Lack of funding has
delayed follow-up studies.

‘This is the only approach that shows any long-term significant effect,’
says Kruck. ‘Most other treatments are aimed at treating the symptoms while
the disease marches on. The treatment we have focused on is to stop the
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McLachlan, leader of the study and director of the University of Toronto’s
centre for research in neurodegenerative diseases, has for years refused
to comment on the possible link between aluminium in the environment and
Alzheimer’s disease. This latest study, and a growing body of epidemiological
evidence, has convinced him that there is now enough evidence to call for
governments to investigate the amount of aluminium people are exposed to
in food, the air, water supplies and even in cosmetics.