Alzheimer’s may be transmissible through blood transfusions and medical accidents in the same way as Creuzfeldt Jakob Disease (CJD)

September 10, 2015 6:47 pm

 Alzheimer’s may be transmissible through blood transfusions and medical accidents. Photo / Supplied

Alzheimer’s disease may be transmissible through blood transfusions
and medical accidents in the same way as Creuzfeldt Jakob Disease (CJD),
scientists believe.
In a landmark finding described as a
“paradigm shift”, researchers at University College London said it was
possible that the “seeds” of dementia could be transferred from the
brain tissue of one person to another.
Worryingly, the proteins
causing dementia are a type called prions which can stick to metal
surfaces, like surgical instruments, and are resistant to conventional
sterilisation.
It means that it would be theoretically possible
to become infected with Alzheimer’s seeds through a blood transfusion,
brain surgery, or invasive dental work, like a root canal operation. And
because the incubation period can be up to 40 years, people could be
unaware that they have been contaminated.

British scientists stumbled on the discovery while studying
the brains of eight people who died of CJD. All had developed the
disease after being injected with human growth hormone taken from bodies
between 1958 and 1985, whereafter the practice was banned.
Unexpectedly,
four of the patients had huge levels of amyloid beta protein – a sticky
deposit which forms among brain cells and stops them communicating with
each other properly in Alzheimer’s patients. Smaller amounts were found
in three others. Although none had developed dementia, scientists say
it is likely they would have, had they lived longer.
“What we
need to consider is that in addition to there being sporadic Alzheimer’s
disease and inherited or familial Alzheimer’s disease, there could also
be acquired forms of Alzheimer’s disease,” said lead scientist
Professor John Collinge, director of the Medical Research Council Prion
Unit at UCL.
“You could have three different ways you have these
protein seeds generated in your brain. Either they happen spontaneously,
an unlucky event as you age, or you have got a faulty gene, or you’ve
been exposed to a medical accident. That’s what we’re hypothesising.
It’s a paradigm shift.
“What relevance this has to common forms
of Alzheimer’s disease out there, we don’t know. Could a small
percentage of these cases be related to seeds from the environment?”
Previous
experiments on laboratory mice and monkeys had already shown
transmission of the Alzheimer’s protein is theoretically possible.
The
scientists are confident the amyloid beta deposits were not caused by
CJD. Brains of 116 patients with prion diseases who had not received
pituitary growth hormone did not have the Alzheimer’s hallmark. Writing
in the journal Nature, the study authors conclude it was likely
infectious Alzheimer’s proteins were passed at the same time as CJD.
“Alzheimer’s
protein seeds could follow similar transmission pathways,” added
Collinge. “The seeds will potentially stick to metal surfaces whatever
the instrument is. With prions, we know quite a lot about that.
Certainly, there are potential risks with dentistry where it’s impacting
on nervous tissue, for example root canal treatments.
“If you
are speculating that amyloid beta seeds might be transferred by
instruments, one would have to consider whether certain types of dental
procedure might be relevant.” Although the risk is low, the researchers
said that determining whether the proteins could be passed through
medical instruments and metal surfaces should be a research priority.
However
the authors urge people not to be concerned about planned medical
procedures, and to dismiss any notion of Alzheimer’s being “contagious”
in the same way as flu.
“No way is this suggesting that Alzheimer’s is a contagious disease,” he said.
“You
can’t catch it by living with someone who has Alzheimer’s disease or
being a carer. No one should consider cancelling or delaying any kind of
surgery. But I think it would be prudent to do some research in this
area.”
Professor Roger Morris, Professor of Molecular
Neurobiology, King’s College London, said: “This is a landmark paper in
providing evidence, for the first time in man, of a mechanism for the
propagation of Alzheimer’s disease that we already know exists from
experimental studies in mice.”
However, experts said that the risks were extremely low and people should not be overly concerned by the findings.
Paradigm shift
• Alzheimer’s is the most common form of dementia, accounting for around 62 per cent of all diagnosed cases.

Dementia is a loose term used to describe different degenerative
disorders that trigger a gradual loss of thinking, remembering and
reasoning.
• In most people, symptoms first appear in their mid-60s. The disease is progressive and incurable.

There are treatments to reduce symptoms. Scientists believe genetic,
lifestyle and environmental factors all play a role in causing it.

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