If that's all it is, just giving the highest dose possible, why not start the trial immediately? Clearly Anavex wants more data because that alone is not sufficient to go ahead full speed. There could be lots of other factors other than dosage that makes one group respond more than another.
I do agree that the best way to play this is to invest, and hold, for at least two years.
Don’t forget the puzzling outliers. One on low blood concentration doing well another on high concentration not so much.
It is not completely straightforward. One hopes the gene and gut profiling holds the clues. This is taking time to figure out or to procrastinate over if no clear explanation emerge.