The PDD phase 2 patients are actually older than AD 2b/3 patients. It’s a surprise AD trials had a proper dose issue. Clearly AD patients are more fragile than PD.
Waiting for Rett is correct strategy imo. Rett has better chance to succeed. If Rett succeeds, it can be used as either off-label use or a tiebreaker for AD. Even if Rett TLR not a clear cut success, Anavex has the short PD p3 trial to fall back to.
There is no reason to risk precious capital on the hardest indication knowing other easier indications are out there. AD was a wrong indication to work on first imo.