The study fulltext is free:
http://stm.sciencemag.org/content/7/278/278ra33.full
The mechanism claims to be that the SUS merely selectively opens the blood-brain barrier long enough for microbubbles to pass through, implying (as I read it) that their action is mechanical.
First ad campaign: "Scrubbing Bubbles -- not just for bathroom surfaces anymore!"
The plague serves a primary purpose of regulating voltage between neurons like a buffer, but now according to this study it looks like it serves a secondary purpose like an immune reaction to disease but it gets out of control and causes alzheimers, so removing the plaque cures the alzheimers but that's not getting the underlying cause which this study says is the disease.
It's fantastic research and hopefully will provide a lot of hope to people and their familes suffering from it.