I don't know how many guys are hanging around here, but here is something I learned a few months ago:
Flomax (tamsulosin), commonly taken to alleviate urinary constriction due to enlarged prostate, et al, causes some fairly significant side-effects. The most notable of these is nasal congestion. But there is another drug, alfuzosin, which is almost as effective as Flomax while causing very little (if any) nasal congestion.
But more interesting still is the fact that when I began taking alfuzosin a significant amount of my "brain fog" cleared up. It's not clear whether this is simply due to not being congested, or maybe due to some other side-effect, but whatever it is, it's goodness!
So if you're taking Flomax, talk to your doc about alfuzosin.