Posted on September 22, 2015
Tags: Alzheimer's Disease, amyloid pathology, ask for evidence, disease transmission, evidence evaluation, health in the media, neurodegenerative disease, observational studies, public health, science in the media
If you’ve read a newspaper or seen the news over the couple of weeks there’s a good chance you’ll have seen a few pretty terrifying headlines related to Alzheimer’s disease…
So can you really catch Alzheimer’s disease from blood transfusions, dental visits or surgery? In short: no.
Here’s how we know:
8 patients were studied in a purely observational manner; there was no randomisation, control group or blinding. The data is comprised of autopsy results of 8 people who were exposed to human growth hormone. 6 of the brains displayed evidence of amyloid pathology (1). A misfolded form of beta-amyloid protein is associated with Alzheimer’s disease (2).
The patients in the study all received growth hormone treatment as children. The hormone was made using parts of the brain from people who had died, and was given to people of short stature via injection. This practice was discontinued in 1985 after links to development of Creutzfeldt-Jakob Disease (CJD). If you have not had this medical procedure then you really should not be worried.
All the patients involved in this study sadly died of CJD, 6 of the 8 exhibited amyloid pathology (1). Let’s be clear here; amyloid pathology is not the only thing involved in Alzheimer’s disease. Tau protein is also a hallmark of the disease, and is usually seen alongside amyloid pathology (3).
The concern is that the amyloid plaques seen in the brain of growth hormone patients may have been due to a contamination in the hormone extracts from cadavers (1). Essentially this an error related to a discontinued technique. This error which raises concerns that transmission of Alzheimer’s disease is possible when tissue from affected patients is directly introduced (in this case via injection), into the brains of patients without Alzheimer’s disease.
If we routinely transfer brain tissue from Alzheimer’s disease patients to patients not suffering from the disease, that’s when we need to start worrying.