[DavidSJ]

I’m having a more difficult time understanding why one would suggest these drugs to a diagnosed Alzheimer’s patient at a point where it can no longer help.

My central claim is the the drugs help quite a lot, by slowing down the disease progression by 30%, and that it's highly misleading to say "only 0.45 points benefit on an 18 point scale", since literally 100% halting of the disease could only have achieved 1.66 points efficacy in the 18 month clinical trial.

This is like having a 100-point measure of cardiovascular health, where patients start at 90 points and are expected to worsen by 10 points per year, eventually dying after 9 years. If patients given some treatment only worsen by 7 points per year instead of 10, would you say "only 3 points benefit on a 100 point scale"?

Or is the long term thought that drugs like these will eventually be used a lot earlier as a prophylactic to those at high risk?

I do believe that they will be more (close to 100%) efficacious when used in this way, yes.