Alzheimer’s disease may have been transmitted by human growth hormone treatments, British researchers reported last night.
The findings led to speculation the disease might also be transmitted by surgical or dental instruments – but the researchers said there is no evidence for this yet.
The research, published in Nature, involves studies conducted at the University of Tubingen, Germany, and at University College, London.
Scientists said there could be a similar mechanism to that which caused the spread of Creutzfeldt-Jakob disease through HGH treatments.
CJD is known to be transmitted through prions and the reports suggest there could be transmission through amyloid-beta "seeds".
The findings emerged from a post-mortem study of eight people who died from CJD, thought to have been contracted from growth hormone treatments. Six of them showed signs of amyloid disease.
Neuroscientist Professor John Collinge, who led the work in London, said last night: “Our findings relate to the specific circumstance of cadaver-derived human growth hormone injections, a treatment that was discontinued many years ago.
"It is possible our findings might be relevant to some other medical or surgical procedures, but evaluating what risk, if any, there might be requires much further research. Our current data have no bearing on dental surgery and certainly do not argue that dentistry poses a risk of Alzheimer’s disease.”
He said that little is currently known about how the amyloid-beta seeds might be spread around the body – whereas CJD was studied extensively to identify where prions might be found.
The Royal College of Surgeons said the UK already has guidelines aimed at preventing the transmission of CJD.
Richard Kerr, who is a college council member and president of the Society of British Neurological Surgeons, 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 of course will inform any clinical decisions that need to be taken to manage and reduce even the smallest risk to patients."
The dean of the college’s faculty of dental surgery Professor Nigel Hunt said: "This is new research in a field of relatively recent scientific enquiry that needs to be taken seriously with further research to inform any changes to all clinical and dental practice.
“In dentistry, patients are protected from infection risks through the widespread use of single use instruments."
Nature 10 September 2015; 525, 165–166; doi:10.1038/525165a [abstract]
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