Yes, absolutely, and that's the part that bugs me most but I've found that I can work around most of it. For instance, I'm a touch typist and used to be able to type nearly flawless, but now I have to proofread even the smallest communications because there typically will be a couple of obvious errors in it. Highly frustrating. Short term memory issues can be dealt with though note taking.
Now, who is to say that the two are related, this is obviously anecdotal and the one might have easily happened without the other, I had some pretty bad O2 dips though and before everything was fine. So for me the correlation is strong enough to believe there is a connection. But the physical aspect is so strong that for me that is 1:1 related for sure. The mental part is not such an easy to point out difference, it is far more subtle.
Fogginess is an excellent description by the way, that's exactly it.