Contagious Alzheimer's

Fear-mongering: Contractable Alzheimer's

Just a quick post in the wake of the ‘news’ of the morning. The media is highly abuzz with the results of a preliminary study indicating that Alzheimer’s may be contracted from surgery.

Alzheimer’s Disease

Alzheimer’s is a neurological disorder causing death of the brain cells, which leads to cognitive decline, including, most famously, memory loss. The disease is classed as a form of dementia and is a progressive disease. That is, it starts off with small effects and gets worse over time. The cause of this disease is one of those ‘poorly understood’ diseases. Scientific consensus is on the understanding that the risk is genetic, with multiple genes being involved in the process. There are no treatments (currently) to stop the disease progressing.

The Media

This morning, the media was fuelled with a study published in Nature, which we will come onto later.
The “seeds” of Alzheimer’s disease may be transmitted from one person to another during certain medical procedures, scientists have found.

            A study into people who died of a separate kind of brain disease after receiving injections of human growth hormone suggests that Alzheimer’s may also be a transmissible disease.

          The findings have raised questions about the safety of some medical procedures, possibly including blood transfusions and invasive dental treatment, which may involve the transfer of contaminated tissues or surgical equipment.

Many of the headlines use the words ‘Alzheimer’s can be caused by surgery’, fear-mongering at its best. Surgery is a terrifying procedure at the best of times, ad the risk of a debilitating disease to this and then you have a no-go area. Once again, the paper is not cited, but easy to find given its infamous nature.

The Study

The study in question was published in Nature journal entitled: Evidence for Human Transmission of Amyloid-β pathology and Cerebral Amyloid Angiopathy (Jaunmuktane, et al.). Looked into the pathology of 8 people who had recently died, all of which had been given growth hormone injections as children. Within the brain, the autopsy found that there was severe grey matter and vascular amyloid-B pathology, which is typical of what is seen in Alzheimer’s patients. Essentially, the protein beta-amyloid was present in 7 of the 8 subjects brains. Four of the subjects had widespread deposits.

That is the crux of this study; these 8 people had grey matter typical with that of Alzheimer’s disease. The only registered thing in common with these people was the fact they had been injected with growth hormone as children.  Is it a possibility that these people just had the protein, and there is no way of saying that they would have gone on to develop Alzheimer's disease. This is a major question in studies with such small sample sets; an estimated 5.3 million people in America alone (hard to find exact figures for U.K. or the rest of the world) have Alzheimer’s disease, which was in 2005. Then surely as the increasing likelihood of more people having surgery, by the preliminary study results:- that should be much higher. However, it is seldom to find the the beta-amyloid deposits in the brains of people with this age range (36-51), although the deposits can occur with natural aging. The aim of the study was to find a suggestion as to how Alzheimer’s and Parkinson’s can spread between cells. Not to see if the diseases can be contracted contagiously.

Conclusion

There is no evidence that Alzheimer's is a contagious disease, in fact, this is even addressed in the study:

         While there is no suggestion that Alzheimer’s disease is a contagious disease and no supportive evidence from epidemiological studies that Alzheimer’s disease is transmissible, notably by blood transfusion, our findings should prompt consideration of whether other known iatrogenic routes of prion transmission, including surgical instruments and blood products, may also be relevant to Aβ and other proteopathic seeds seen in neurodegenerative diseases.

This is a study, which is highly speculative, that has been picked up by the media and taken to the hills. There is little evidence to suggest that growth hormone or surgery induce Alzheimer’s. They even state this in the study. This study uses 8 subjects, 8. In a study like this numbers are everything. This is a preliminary study and should be approached with a high amount of caution. I’m not saying that they’re not correct and the study is useless, this could be proven to be true after a high amount of reproducability., this however, given the pathology of Alzheimer’s is highly improbable. It is hard to ascertain where they have got the theory of Alzheimer’s being contracted by surgical instruments is from. It genuinely just appears to have been thrown into the mix randomly.

Note here, my fault is not overly with the study. Let me hammer this home: this is a preliminary study. This is a study, which is set out in order for more research into other various areas. However, I believe their conclusions are a little miss-matched and appear to have a slight redictio ad absurdum fallacy. No, my fault is with the headlines and the media. My grandmother has a terrible fear of Alzheimer’s and constantly asks me questions about it. I know, at some point today (surprised it hasn’t happened already) that I will be contacted about this, as it is so prolific in the media at the moment and making headlines. I’m sure there will be many people worried about this, but really, think about the height of the study. There was 8 subjects, that reveals very little at this moment other than possibly how Alzheimer’s can spread between cells. That is all.