How do you know it's completely arrested?

Best these type of drugs can do is give you a few months extra window (say 4-6 months). They're not a cure. Sadly.

Completely arrested? I don't. But it appears to be arrested in ways that matter for mental acuity, for now. I've taken care of a parent with Alzheimer's, and helped several other caregivers over the years with their own family's journeys, and one thing I can tell you is that I have never, ever seen an actual halting of the progression for this long. The descent is usually a stairstep pattern, but the steps are on the matter of weeks to a month or two. My friend has been stable for a year.

This is all new. There is research hinting at Alzheimer's subtypes, some of which are more likely to respond than others. Even halting the decline is a huge potential breakthrough.

That's 4–6 months in the 18 months the trials lasted for, i.e. about a 30% slowdown of progression. The open-label extensions suggest this relative slowdown seems to continue at least to the 4-year mark (at which point it would have bought you over a year of time): https://www.alzforum.org/news/conference-coverage/signs-last...

Time will tell if the 30% slowdown continues beyond four years, and/or if earlier treatment with more effective amyloid clearance from newer drugs has greater effects. The science suggests it should.

The way I’ve watched Alzheimer’s work in a family member is that it’s a step down function rather than gradual. And once something is lost, it doesn’t come back. So anything that can delay the next step even just for months is a win right now.

They tell you this:

> her mental acuity scores are (slightly) better than they were last year