I think we're going to have to study all of this for a while to figure out the full meaning of this presentation.
First of all - Anavex is proposing restoration of these microbiota as a biomarker for recovery.
I think what may be going on here is that the accumulation toxic waste in the system suppresses the microbiome and restoration of homeostasis allows it to recover.
I also think it's possible that Eisai's plaque drug will need a 2-73 assist if it is to do anything.
So the correct answer may be "both", that as the gut recovers 2-73 begins to work better. I really don't know yet.
There is NOTHING in the presentation that even REMOTELY hints that A-273 affects the biome. Rather the conclusion drawn from the limited derivative data may only be that optimal absorption, allowing increased serum concentration, is dependent upon restoring bacterial balance.
THAT narrative has long been touted by more than scientific investigation. Seems logical it would assist whatever benefits may ultimately be verified from 2-73 dosage.