Cocoa preventing Dementia?

http://www.independent.ie/lifestyle/health/hot-chocolate-can-prevent-onset-of-dementia-in-elderly-29483327.html
http://www.cbsnews.com/8301-204_162-57597454/two-cups-of-hot-cocoa-a-day-sharpens-seniors-brains-study-suggests/
http://www.webmd.boots.com/alzheimers/news/20130808/cocoa-older-minds-sharper
http://www.examiner.com/article/research-hot-cocoa-is-good-for-your-brain?cid=rss
http://www.telegraph.co.uk/health/healthnews/10228145/Two-cups-of-cocoa-a-day-may-boost-memory.html