One thing to keep in mind is that cognitive functions can be due to many things, including just normal fluctuations. No one is equally sharp all the time. What I had while drinking and for a couple months off and on after stopping was an annoyingly short attention span, it was hard to focus on anything for longer periods of time. It one quite a torture because I could not afford to just relax, had a lot of work to do with deadlines etc. It cleared up after a few months.