Cocoa polyphenols enhance positive mood states but not cognitive performance: a randomized, placebo-controlled trial
Journal of Psychopharmacology (2013) - Comment
pubmed: 23364814  doi: 10.1177/0269881112473791  issn: 1461-7285  issn: 0269-8811 

Matthew P Pase, Andrew B Scholey, Andrew Pipingas, Marni Kras, Karen Nolidin, Amy Gibbs, Keith Wesnes, Con Stough