well I came across this study:
http://www.fasebj.or.../9/962.full.pdf
Basically it says that l-dopa, dopamine and epinephrine not only inhibit the growth of amyloid, but also disaggregate it.
Its an in vivo study.
We also know that treatment with l-dopa has a lot of side effects which treatment with mucuna pruriens seed does not have. And mp replenishes catecholamine levels, while l-dopa does only increase dopamine.
mp is also neuroprotective, while l-dopa isn't.
Now it isn't a whole cure though - amyloid is neurotoxic to neurons exposed to it, so treatment with mucuna pruriens would likely only prevent further damage, and give already damaged but not dead neurons the chance to recover since amyloid stress would decrease.
Once amyloid is on the decrease, a therapy could include substances which allow the brain to regenerate and so further improve the mental state.
Sounds as an effective means of preventing alzheimers to me, though.