http://www.sciencedirect.com/science/article/pii/S1053810012000037
Just one example of such an article and I am too lazy to find more now, but I have heard of a good bit of research of drinking and focus/problem solving ability.
I drink slowly while I play. It has been shown that creative problem solving tends to be improved and carried out more quickly with low levels of blood alcohol. I won't get in to the theory, but I am sure you can find references if you look. The above is a peer reviewed article expressing these views, not something from healthnewsdaily.com or some bogus website.
Throughout undergraduate and graduate school, I sipped scotch while I studied (organic chemistry--very creative and intensive field of study). I found it to be helpful. With all that said, it has also been shown that alcohol negatively affects motor skills. Hand eye coordination, reaction speed, etc. are all diminished. Luckily, poker does not rely on quickly throwing in your chips and would be a more intellectual problem solving endeavor that may benefit from low level of blood alcohol.
For those that say NEVER DRINK OMG...as poker players, we rely heavily on the science of math. Rather than pretend to know exactly how alcohol may affect ones body and brain at the table, you could again rely on the science of those who have done the studies by doing a few quick online searches. I find science is a bit more sound that one's own opinion who is not involved in the field. (That isn't meant to sound rude, so I apologize if there appears to be a negative tone).