The author, Jonah Lehrer, has an amazing book on behavior economics that I considering a must read for anyone trying to sell anything. It's been incredibly valuable to us at Wistia. It's called "How We Decide".
Jonah always finds incredibly interesting ways to pull apart behavior from a neurological perspective.
http://www.amazon.com/How-We-Decide-Jonah-Lehrer/dp/05472479...
I would say it's good to read his stuff as a jumping off point, but it may be good to follow that with something more scientific on the subject.
The whole premise of this piece doesn't make sense to me - coffee, whatever else is in Redbull - provide energy, not focus. That energy can be used to focus on something you don't want to focus upon. You also can let your mind wander at the frenetic pace stimulants like coffee, ADHD meds and others facilitate. So back to the beginning - Jonah Lehrer is very good at nicely framing a point that he isn't actually making.