(Full disclosure: I have been involved in MRI and PET imaging arms of industry-funded trials such as this one). First off, there's no question that Amyloid pla

(Full disclosure: I have been involved in MRI and PET imaging arms of industry-funded trials such as this one). First off, there's no question that Amyloid plays a role in the development of AD. It is however becoming increasingly clear that it does not play the primary causative role. Its exact role is currently unclear: its likely both a secondary neurotoxic agent and an epiphenomenon. It's also non-specific (ie. Amyloid deposition is seen in several other disease states as well as in many cognitively normal controls). There are certainly other agents and mechanisms that are both more important in the development of AD and arise earlier in the time course of the disease. This particular drug has a modest effect (From this study - it slows down disease progression, at least in the first year). The several dozen other anti-amyloid agents that have been trialled, at billions of dollars of expense, have either had little or no effect or demonstrated a modest effect in the first 12-24 months treatment before becoming ineffective again. Its also worth noting that the manufacturers have a very limited understanding of the mechanism(s) of action of the drug. So, there's no guarantee that any effect is actually attributable to the reduced amyloid deposition, and not some secondary process.