[pcrh]

P.S.

As you have demonstrated an interest in this topic, but are not an active researcher, I suggest that you become familiar with Alzforum [www.alzforum.org]. It provides reputable summaries and comments from leading researchers on topical issues and papers in Alzheimer's and related neurodegenerative diseases.

They're still fairly technical, but not as dense as the original papers. Here is an example related to our discussion: https://www.alzforum.org/news/research-news/app-c-terminal-f...

[DavidSJ]

I've been a regular reader of Alzforum, and cite multiple of their articles in the blog post that was linked up above. https://www.astralcodexten.com/p/in-defense-of-the-amyloid-h...

[pcrh]

Thanks for the article.

I actually read your article some time ago, having found it via SSC. One comment I would make is that the pathology and genetics of AD implicate APP without much doubt. In the field, there isn't much argument against it, even by those who work on tau. Divergences in opinion more often focus on which is the better target for drug therapy.

For example, Derek Lowe's articles on AD do not argue against an APP-tau-neurodegeneration pathway (I am a regular reader of his blog), but argue that targeting amyloid is unlikely to work as a drug therapy. This argument is sometimes extended by Lowe and others to questioning whether Aβ per se is the agent that triggers the downstream effects of either mutating APP or otherwise disrupting its biology. It is possible that Aβ is a by-product of the "true" APP-triggered pathway, see the arguments in favor of C-terminal fragments I linked to earlier.

A fundamental problem the field faces is that it is difficult to experimentally induce actual AD in animals, and so it is difficult to scientifically test hypotheses as to what might cause it. Compare perhaps to something like diabetes. Exactly why mice do not develop realistic AD is unknown.

In addition, there have been literally hundreds of publications (minimum 300) claiming to reverse "Alzheimer's disease" in mice, and the only ones that have lead to any kind of meager success are those using the antibodies. The arguments made in the 2010 review below by Zahs and Ashe [0] remain mostly true sixteen years later.

The recent clinical trials, e.g. Lecanemab, are of interest not only because they might provide at least some benefit, but also because they might represent the first actual scientific experiments showing that removing Aβ can ameliorate the disease, even if only slightly because of the late stage at which they have so far been tested.

Currently ongoing trials using anti-Aβ antibodies and targeting earlier phases of the disease in those with inherited mutations are of keen interest. If these demonstrate clear prevention of disease progression, then the Aβ hypothesis can be considered tested and proven. If not, then the Aβ hypothesis should be abandoned. This would however still not disprove an APP-focused hypothesis.

[0] 'Too much good news' - are Alzheimer mouse models trying to tell us how to prevent, not cure, Alzheimer's disease? https://alzped.nia.nih.gov/sites/default/files/2022-09/zahs....