I skim through most of the article you posted, and it seems like the combined effects mostly improves alertness and concentration (but I don't know how statistically significant these data are in the first place because I don't know how to interpret them). One of the article clearly shows that this won't help with the PAT, though (lol). It said it won't help with visual ability, mental rotation, and choice making. I usually don't have much of a problem with concentration, but it won't hurt to experiment on myself. Most theanine are sold in bulks, and I can't find any vendors selling low quantity. I might just try mixing green tea with coffee at first if I can't find any low-cost theanine. I will report back in 3 weeks!