No worries, there is no evidence Alzheimer’s disease is infectious

This week, we have witnessed alarmist headlines telling us scientists have discovered that Alzheimer’s can be transmitted from human to human. See, for example, Alzheimer’s disease may be infectious in The Independent, or Evidence for person-to-person transmission of Alzheimer in Scientific American, or Alzheimer’s could spread during surgery in The Guardian.

In less than 24 hours, however, we have seen a backtracking trend on this story, with most media outlets telling us not to worry and not to believe the headlines, and The Independent releasing a new article saying the previous headlines were misleading and could cause unnecessary concerns.

So what happened?

The headlines follow the publication of a study in Nature, one of the most prestigious and authoritative scientific journals, often considered as a publisher of major breakthroughs. The study describes eight patients who received growth hormone  injections (a practice now discontinued) as children and years later died after developing a form of prion disease called iatrogenic Creutzfeldt-Jakob Disease (iCJD). It investigated how the injection may have affected the brain of these patients who displayed brain changes similar to those observed in people with Alzheimer’s. None of the eight patients were diagnosed with Alzheimer’s disease. The press release by University College London (UCL), the institution where the scientists leading the study are based, stated “There were no signs of the tau protein pathology characteristic of AD [Alzheimer’s disease], but the full neuropathology of AD could potentially have developed had the patients lived longer”. It quotes Prof Collinge, one of the lead authors, as saying: “Our current data have no bearing on dental surgery and certainly do not argue that dentistry poses a risk of Alzheimer’s disease” and Prof Mike Hanna, Director of the UCL Institute of Neurology: “It [this research] could inform our understanding of the molecular mechanisms leading to Alzheimer’s disease“. In other words, while the press release hints at a better understanding of the mechanisms leading to Alzheimer’s disease, it does not suggest the disease is infectious.

The research has the potential to change how we study and understand neurodegenerative processes, but its merits have been completely mis-reported in the media. Journalists have instead preferred to focus on what would make a story, i.e. telling us that we have to be careful when we undergo surgery because we might ‘catch’ Alzheimer’s disease.

Such headlines did not go unnoticed by experts in the field who immediately raised concerns. The Alzheimer’s Research charity and the NHS felt the need to release statements reassuring there is no need to worry.

Because lots has been said about this study in the latest articles and the statements reported above, as well as blog posts like this one by Kelly Oakes, which clearly explains why there is no cause for concern, I will not repeat the arguments here. In a nutshell, this study was based only on eight patients who received a procedure that was stopped in 1985 and presented some brain features also observed in patients with Alzheimer’s disease, although they were never diagnosed with this pathology.

Instead, I want to highlight once again the potentially damaging effect of spreading unfounded fears among the population reading the news. Alarmist headlines could make people reluctant to undergo a surgical treatment because of the fear of contracting Alzheimer’s disease. A similar scenario led to the decrease in MMR vaccination uptake because parents worried that their children might develop autism (you can read here about the MMR vaccination/autism story, which also originated in a study based on eight children).

It is reassuring to see that the headlines have been corrected very promptly by multiple voices. Hopefully, no damage has been done.

Jaunmuktane, Z. et al. (2015). Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy. Nature. DOI: 10.1038/nature15369