There is only a small part of cocoa powder that shows help for the brain. It is cocoa flavanol. M&M/MARS candy is working on ways to isolated and concentrate it for large scale production. Here is a link http://www.marscocoascience.com/cocoa-flavanol-advances.

You can get early versions of it as Cocoavia by Swanson and other brands on Amazon and such. It can be pricey.