Surprise, surprise....the biomarker is lipids, also known as fats. While they don't really say, I would suspect it is the healthy fats that are at play...healthy fats, such as are found in olive oil and nuts and fish. Eat the typical modern diet, horrendously low in healthy fat (and many other things, actually) and risk getting dementia, or eat lots of healthy fats like our ancestors did and see how you do, nothing to lose and everything to gain.
here's the link:
http://www.cnn.com/2014/03/09/health...html?hpt=hp_t2