1. If certain Prion disease(like say CJD) was Communicable with a high R0[1] by say contact, fecal matter, saliva we would see a lot of people dying, since CJD has a mortality rate of 90% within 1 year[2].

2. The level of A-beta protein(i.e. not technically prion just yet) again the deposits in 7 of the 8 patients was so severe that if this were communicable easily with a high R0, it would also be seen in the general population by now.

So one does not need to worry at least about communicability of this through those means just yet. But transmission if postulated experimentally through certain means like say dental health can mean that we might be able to put a dent in a health crisis of a greying population.

[1] https://en.wikipedia.org/wiki/Basic_reproduction_number [2]https://en.wikipedia.org/wiki/Creutzfeldt%E2%80%93Jakob_dise...

1. CJD is only one specific instance of Prion disease. Others (e.g. vCJD) have incubation periods of - multiple decades -. From the article: "In the original Alzheimer’s transmissibility study, scientists examined the brains of eight patients treated with prion-contaminated human growth hormone as children who decades later died from prion disease"

Alzheimers is growing at epidemic proportions, globally [1].

Alzheimers in the US is growing at alarming rates [2].

[1] https://www.alzheimers.net/alzheimers-is-on-the-rise-in-thes...

[2] https://www.alz.org/alzheimers-dementia/facts-figures

  Alzheimers in the US is growing at alarming rates

Is occurrence increasing alarmingly, or is it just being more properly diagnosed? "Senility" and "old age" may not have been properly isolated last century.

I do wish those numbers controlled for population size, and rates of known correlated variables (e.g. diabetes).

What I want to know is whether the probability of developing the disease given I am a X year old healthy male/female has increased.

The article mentions that explicitly though [0]

It also doesn’t mean it’s not communicable or contagious, it means we don’t know because it seems no one have looked yet [1]

[0] It is important – imperative – to emphasize that transmissible does not equal contagious. There is absolutely no evidence that people with dementia can spread their disease casually to people around them.

[1] Since Alzheimer’s Disease is so common, and we have not (to my knowledge) been looking for Alzheimer's caused by surgical or other medical procedures that access eye or neural tissue -- particularly in patients for whom the appearance of Alzheimer’s would not be surprising -- is it possible that we are underestimating the transmission potential of this disease, and that such events are less rare than we would guess?

(1) thanks for clarifying, that's a relief. (2) what does transmissible mean, then?

As far as I can tell, the two words mean the same thing. The other commenter may have meant to contrast with “contagious,” which means that it’s not just possible but reasonably easy to transmit the disease. From the article:

“It is important – imperative – to emphasize that transmissible does not equal contagious. There is absolutely no evidence that people with dementia can spread their disease casually to people around them. Even donated blood appears to be safe, as no association with blood transfusions and Alzheimer’s Disease has ever been detected.”

Could be wrong but communicable means you can infect other people around you. Transmissible means the disease does generalize to some extent and is caused by something replicable. That is, if they take some of the prions infecting you and inject it into someone else, it can infect someone else. Broken arms and bad genes aren’t transmissible. Lots of cancers aren’t either (meaning I can’t inject you with my cancer and infect you)

This isn’t especially surprising. It’s about on par with Alzheimer’s being caused by a microorganism. If we accept that this is true, then it follows that Alzheimer’s, as a symptom, can be transmitted. But unless there is a noteworthy vector of transmission, there’s nothing to worry about.

Speculation about eye care equipment sounds like sensationalism until tested.

Not the same terms per se, but if you are one there is a massively greater chance that you might be the other too. This is an area where we should perhaps be wary.

If evidence of transmission between people comes forward, the sociological implications will mean decades of debate. Im not going to fault anyone for taking a keen interest in this area. They are opening a pandora's box.

> Just a clarifying point from the article: Transmissible != Communicable

That's a good point for those who just skip straight to the comments, but you should edit this to use the language of the article (contagious vs communicable)