You missed the point. Even if there is a reduced risk of dementia diseases, there is a huge risk of cancer and other serious diseases. My point was that to get the benefit of any such advantage (if it exists - I don't know one way or the other) then one has to risk dying of cancer and other diseases before one gets the benefit. To me that is as logical as using amalgam - it prevents further decay of the tooth and is one of the most enduring filling materials, but can make someone very ill.