Can you CATCH Alzheimer’s? Disease could be spread via blood transfusions during surgery in the same way as CJD, say scientists
Alzheimer’s disease can be caught from blood transfusions, operations and dental work, it is feared.
A potentially explosive study has provided the first evidence that the devastating condition can, like mad cow disease, spread through ‘medical accidents’.
The British researcher, Professor John Collinge, said we ‘need to rethink our view of Alzheimer’s and evaluate the risk of it being transmitted inadvertently to patients’.
One of the UK’s leading brain surgeons warned that we don’t know if the techniques used sterilise medical instruments are effective and said that the research ‘must be taken seriously’.
However, others urged caution, saying the study was small and it does not prove that Alzheimer’s disease is contagious.
At least 500,000 Britons are living with the incurable condition and, until now, it was thought it was either caused by faulty genes or a combination of bad luck and ageing.
Professor Collinge, of University College London stumbled on the link with Alzheimer’s when inspecting the brains of eight people who had died from CJD, the human form of mad cow disease.
They had caught CJD after being given injections of human hormones as children to treat growth problems.
To his great surprise, he found a protein that is a hallmark of Alzheimer’s in the brains of seven of the eight of the patients.
In four of them, levels of the memory-robbing amyloid beta protein were ‘severe’.
Writing in the prestigious journal Nature, he said that those studied were aged between 36 and 51 and such brain damage is ‘simply not seen’ in people of that age.
With no evidence that CJD somehow triggers the build-up of the protein, Professor Collinge said the most likely answer is that it, like the CJD, had been lurking in the hormone injections.
None had actually developed full-blown Alzheimer’s but they may have done if they had lived longer.
Some 1,850 British children with growth problems were treated with hormones extracted from ground up brain tissue before the procedure was banned in 1985.
Around 1,500 are still alive and Professor Collinge said some of them may still develop Alzheimer’s disease.
Worryingly, there is no complete record of who was treated – meaning many will have had no advance warning of the bombshell.
The study also has implications for the wider population.
Professor Collinge said the similarities between the amyloid beta protein of Alzheimer’s and the prion protein that causes CJD means we must question if the two can spread in the same way.
He said it is possible that contaminated medical instruments, blood transfusions and dentistry could all lead to the amyloid beta protein being passed from one person to the next.
The protein ‘sticks avidly’ to metal surfaces, such as surgical instruments, and it isn’t clear if it is killed off by conventional sterilisation techniques.
In no way does this suggest that Alzheimer’s disease is in any way contagious. You can’t catch it by living with someone with Alzheimer’s disease or by caring for someone with Alzheimer’s disease
Professor John Collinge, UCL
Professor Collinge said that while transmission by blood transfusions is ‘possible’, surgical contamination is a bigger threat.
Even dentistry can’t be given the all clear.
The professor said: ‘I think one would have to consider whether certain types of dental treatment are relevant’, adding that more research would be ‘prudent’.
However, he stressed that he had not proved that the seeds of Alzheimer’s can be passed from person to person and urged people not to panic.
Professor Collinge said: ‘In terms of people worrying about this, it is important you understand that this relates to a very special situation, where people have been injected with extracts of human tissue.
‘In no way does this suggest that Alzheimer’s disease is in any way contagious.
‘You can’t catch it by living with someone with Alzheimer’s disease or by caring for someone with Alzheimer’s disease.
‘I don’t think anyone should delay or rethink having surgery on the basis of this finding.
‘I don’t think that any immediate action needs to be taken.’
Richard Kerr, president of the Society of British Neurological Surgeons and a consultant brain surgeon, said: ‘This is new information in a field of highly complex scientific enquiry that needs to be taken seriously.
With such a small study, however, further research is needed so we can learn more about transfer and whether existing decontamination procedures are effective.
‘This will inform any clinical decisions that need to be taken to manage and reduce even the smallest risk to patients.’
Masud Husain, an Oxford University professor of neurology, described the research as ‘beautiful’ but cautioned it must be kept in context.