> For a disease which (to my knowledge) can’t be slowed down or reversed

There's Lecanemab and Donanemab. The effects are modest however.

Trontinemab is in trials right now and has 92% of patients achieving low amyloid levels. And more people should be able to take it as it causes less brain swelling (ARIA-E). I'm unaffiliated, I just follow medical research in my free time. But I'm quite hopeful about this medication