A study published in the medical journal Nature has provoked media coverage. The study speculated that it might be possible to transmit Alzheimer's disease during certain surgical procedures.
What did the study find?
The study looked at the brains of eight people who had died of Creutzfeldt-Jakob disease (CJD) during the 1970s following treatment with brain-derived human growth hormone (HGH). HGH is used to treat short stature and, before the risks of CJD were fully known, was derived from the brain tissue of deceased donors, some of whom had CJD.
The research team found that in four out of the eight brains studied there were also signs associated with Alzheimer's disease. As these people were outside the age range associated with such signs, the researchers speculate that Alzheimer's might also have been transmitted by the same route as the CJD.
They theorise that it could be possible for Alzheimer's disease to be transmitted by instruments used in brain surgery that are contaminated with infected brain material.
This was a small study and this is not evidence that Alzheimer's disease can be transmitted during neurosurgery or any other form of treatment. There is no suggestion that Alzheimer's disease is contagious.
NHS procedures have improved significantly since the 1970s when these patients contracted CJD. Modern surgical equipment used in the UK is very safe and the NHS has extremely stringent procedures to make sure of this.
Chief Medical Officer Professor Dame Sally Davies said: "There is no evidence that Alzheimer's disease can be transmitted in humans, nor is there any evidence that Alzheimer's disease can be transmitted through any medical procedure. This was a small study on only eight samples. We monitor research closely and there is a large research programme in place to help us understand and respond to the challenges of Alzheimer's. I can reassure people that the NHS has extremely stringent procedures in place to minimise infection risk from surgical equipment, and patients are very well protected."
Dr Doug Brown, director of research at Alzheimer's Society, said: "There are too many unknowns in this small, observational study of eight brains to draw any conclusions about whether Alzheimer’s disease can be transmitted this way."
A statement from the National Prion Clinic said "There is absolutely no suggestion from our work that Alzheimer's is a contagious disease or that there would be any risk to relatives, spouses or carers of patients with Alzheimer's"
I've just had growth hormone treatment – will I develop Alzheimer's?
From 1985, the use of brain-derived human growth hormone stopped and a synthetic version was used instead. Modern treatments are regulated, licensed and considered extremely safe. No contagious disease is associated with these modern treatments.
I had human growth hormone treatment before 1985 – what should I do?
All individuals treated with contaminated hormone were informed in the late 1980s about the possibility of developing CJD as a result, so if you did receive this type of treatment you should already know. The contaminated hormone was withdrawn from use in the UK in June 1985 and any treatments that began after this date will have used synthetic hormone only and cannot have been contaminated in this way. If you remain uncertain please speak to your doctor.
If your doctor is unsure, he or she can contact Dr Peter Adlard at the UCL Institute of Child Health in London on 020 7404 0536. Dr Adlard is responsible for keeping records of all people treated in the UK with human-derived growth hormone. He also provides advice about the risk of CJD and counselling support to this group and their families.
I've recently had surgery – does that mean I'm at increased risk?
As the paper itself says, there is no suggestion that Alzheimer's disease is contagious.
There has so far been no evidence of Alzheimer's disease being transmitted through surgery. This study has made a possible link in four cases of specific treatment with growth hormone before 1985, but it is important not to jump to conclusions about what this important, but small, research study might mean.
There has never been a proven case of transmission by neurosurgery.
Modern surgical equipment in the UK is very safe and the NHS has extremely stringent procedures to make sure of this. These include using single-use instruments where possible, and developing special equipment that reduces the risk of contamination. If single-use instruments cannot be used, then there are processes in place to track the use of specialist equipment.
NHS procedures have improved significantly since the 1970s and 1980s, which is when patients in this study contracted CJD. Procedures in the NHS now are extremely safe and patients are well protected.
Might Alzheimer's disease be transmitted by blood transfusion or use of other blood products?
This research only relates to treatment by injection with human pituitary-derived growth hormone. Published studies have looked at this question but have found no evidence that blood transfusion is a risk.
Links to the headlines
The Telegraph, 9 September 2015
Mail Online, 9 September 2015
BBC News, 9 September 2015
Sky News, 10 September 2015
The Independent, 10 September 2015
The Independent, 10 September 2015
Daily Mirror, 10 September 2015
The Guardian, 10 September 2015
ITV News, 10 September 2015
Daily Express, 10 September 2015
Links to the science
Nature. Published online September 9 2015