Attention: chocolate can give you an edge
Do you like chocolate? Don’t feel guilty: a vast majority of people would probably say yes. The popularity of chocolate is indeed easy to understand, if only because it is typically quite sweet, a taste we have evolved to prefer from the times when our ancestors roamed the wild, looking for ripe fruits to eat. But there is more to it. Chocolate also contains ingredients such as tryptophan and phenylethylamine, which stimulate the brain’s pleasure centers. You may have heard, or even experienced first-hand, that eating a chocolate bar can have positive effects on your mood—those ingredients are a primary reason.
Chocolate, or more specifically cocoa, has other molecules that influence your body and brain as well. The most important of these are so-called flavanols. If you consume these regularly for a while, your insulin resistance decreases, which helps prevent diabetes, and your cardiovascular health improves. Flavanols also have neuroprotective effects in elderly people, helping to counter cognitive decline. Good reasons to indulge in some cocoa every now and then!
Even right after consuming a single serving of flavanol rich chocolate, the blood flow in your brain already increases, and if you were mentally fatigued, you recover a little better. Flavanols thus have clear effects on our cognition and brain, but we do not know why exactly. What we do know is that when you consume flavanol-rich chocolate, nitric oxide synthesis is activated in your body. Nitric oxide has many biological functions, two of which may be related to the immediate effects of cocoa flavanols on cognition. First, nitric oxide induces vasodilation, which affects vessels in the brain, and increases blood flow. Second, nitric oxide can act directly, as an actual neurotransmitter in the brain. It seems likely that either or both of these mechanisms could produce improvements in cognitive functions.
Surprisingly, it is also yet unknown what specific cognitive functions are affected by cocoa flavanols. If you experience less mental fatigue, for instance, that could be due to improvements in very different things, from attention to working memory and decision making. Our research aimed to pinpoint this a bit more by charting the effects of flavanols on attention specifically. We chose attention because it is an important cognitive function that we rely on many times a day. For example, on your way to the university you must mind the road for any kamikaze cyclists that might appear. Once there, you need to focus your attention on the fascinating lecture your professor is giving. And back home you will want to concentrate on your textbook, rather than on the lyrics of the heavy metal song your roommate is enjoying.
We did not take half measures in setting up our study. We pre-registered everything beforehand on the Open Science Framework, including the design, our hypotheses, and analysis plan. We completely randomized and counter-balanced the order of our tests, tested every participant in all conditions, and ran the study in double-blind fashion, so that not only our participants, but also the experimenter was unaware of the condition being tested each time. Finally, we made sure we would not be measuring just a placebo effect by comparing our experimental high-flavanol cocoa drinks with both a neutral baseline, and another cocoa drink that looked and tasted the same, but which contained no flavanols.
We tested 24 women and 24 men, each of whom completed close to 3600 experimental trials in four separate sessions (thanks, really!), and we found they were demonstrably faster in our visual search task after they had consumed flavanol-containing cocoa. The visual search task they did was a staple test of spatial attention, in which you need to find specific targets within arrays of other, distracting items, as quickly as you can. For instance, you may be asked to search for a green teddy bear amidst its red brothers, although we used lines rather than teddy bears in our version. Either way, from the flavanol-induced increase in visual search speed we can probably safely conclude that cocoa flavanols enhanced the efficiency of spatial attention, and confirm that consuming cocoa flavanols can indeed improve this aspect of cognition.
So, the next time you are about to hit the road, or actually, the next time you need to attend to anything specifically, ask yourself whether some high-flavanol chocolate might be in order…
Our paper in Psychopharmacology: https://link.springer.com/article/10.1007/s00213-018-4861-4
Our project on the Open Science Framework: https://osf.io/zfg85/
More research from our group: https://elkanakyurek.com