A new study suggests that Alzheimer’s disease can potentially be transferred from one person to another during medical procedures. According to the study proteins of the disease can potentially attach to surgical instruments and be transmitted between individuals.
The findings are the first of dementia transmission in humans through microscopic protein fragments. The findings have led to public concern over the safety of certain medical procedures, most notably dental treatments. Researchers also suggest investigating blood procedures as a precaution.
The discovery was made by British scientists who were investigating a rare form of “iatrogenic” Creutzfeldt Jakob Disease (iCJD), a disease which destroys the brain and has been known to be spread by using contaminated surgical instruments.
The scientists were inspecting the brains of eight patients who had died from iCJD. They were surprised to find that six of the patients bore a clear molecular sign of Alzheimer’s disease. The evidence suggests that Alzheimer’s carrying proteins had been transferred into the brains of the patients, along with iCJD.
Such proteins are known to stick to metal surfaces and resist conventional sterilization. However, it is unknown if the patients would have eventually developed the disease had they been alive.
Previous experiments involving laboratory mice and monkeys have shown that the transmission of the Alzheimer’s protein is possible in theory. Liquefied brain tissue from deceased Alzheimer’s patients was injected into the central nervous system of the animals. After the procedure took place, the animals developed brain changes that are associated with Alzheimer’s disease.
With these findings, dental procedures are of a particular concern. Director of the Medical Research Council Prion Unit at University College London Professor John Collinge said, “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 treatment, and special precautions are taken with reamers that are used in root canal treatment for that reason, in the UK at least.”
Collinge went on to add that there was no epidemiological evidence that suggested that Alzheimer’s could transferred through blood transfusions. That being said, he believes that the issue is worth examining further.
However, Collinge seemed to somewhat backtrack on his statements on dental treatments. He stated, “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."
Collinge went on to stress that people should not be concerned about upcoming medical procedures and that Alzheimer’s is not contagious in the same way as other illnesses, such as the flu. According to the doctor, one cannot obtain Alzheimer’s by simply living with someone who has the disease or by being a caretaker.
Chief medical officer Professor Dame Sally Davies also attempted to reassure the public. She said, “This was a small study on only eight samples. We monitor research closely and there is a large research program 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 minimize infection risk from surgical equipment, and patients are very well protected."
Despite the reassurances from the doctors, there remains concern that Alzheimer’s protein seeds could be transmitted in a similar method as CJD prions. However, chief scientist at the charity Alzheimer's Research UK Dr. Eric Karran remains unconvinced. He says, “The biggest risk factor for Alzheimer's is age, along with genetic and lifestyle factors. If further research was to confirm a link between historical tissue contamination and Alzheimer's, it would only likely be relevant to a tiny proportion of the total number of people affected."
The British Dental Association's scientific adviser Professor Damien Walmsley continues to maintain faith in British dental practices, stating, “Dentists take patient safety very seriously and follow strict protocols to protect patients from the risk of infections, however slight that risk may be. These protocols were strengthened in 2007 when a UK-wide restriction on the re-use of files that come into contact with nervous tissue during root canal treatments was put in place. These measures make dentistry one of the safest areas of healthcare."