Anavex Life Sciences Corp (AVXL)

[Steady_T]

I'm inclined not to think that enthusiasm for 2-73 was a confounding factor. There is no reason to think that the placebo group was any more or less enthusiastic about taking 2-73 than the drug group. After all, the subjects don't know which treatment arm they are in. That is the point of a blinded trial. Each group is led to believe they COULD be taking the drug. So the expectations should be the same in each arm.

To me it seems more likely that there is a high variability in the various measures and if you look at the SE you can see that they are pretty large.
The random variability in the measures broke the wrong way in this trial or perhaps it is what Anavex suspects. Anavex thinks that the placebo arm had a different overall level of disease severity in the placebo arm vs the drug arm and that skewed the results.
For example that FDA discusses the ADAS-COG measures of AD as not being valid until they are taken over a three year period because of the high levels of variability in the measure. It takes a long time to capture the real decline in function.

People have good days and bad days and behavioral measures capture that. If you are taking measures every week or better several times a week then the good day, bad day issue tends to get washed out. But trials don't take measures that frequently. You can imagine the difficulty in getting a Rett girl in a wheel chair dressed and ready for a possibly long car trip to visit the Dr's office for a series of behavioral tests and observations every week. That is a big burden on the girls and the caretakers.