[absolutelastone]

This article is all the supporting evidence without any of the setbacks and failures at reproducing the correlations. There have been attempts at showing benefits with antivirals before. Just not a full-on double-blind study apparently. I recall reading about a study with high doses that showed no benefit for people in early stages.

The 7 years time duration probably comes from the size of the study and also how long it is believed to take to get benefit if there is one. I would think if it really worked they would have stopped early for ethics reasons because they should also give the treatment to the placebo arm rather than watch them decline while knowing how to prevent it.