Absolutely!
When I was first diagnosed with E they put me on Dilantin. I was 27 (now 40) and working in an office and I immediately felt the effects of Dilantin. I actually called the doctor (now I was new to E and didn't know a whole lot about E or meds) and told him he had me on the wrong stuff because I felt like the world slowed down to 5 mph. I actually whispered to him and said, "I feel a little retarded or slow." He responded, "Great, that means it's working." My boss also started noticing I could no longer multi-task, forgetting things, I was always tired and basically my whole personality changed. I continued it because I didn't know about switching to something else and for the most part it did control the seizures, at least for while. I also experienced what I now know to be "brain fog" which I could never describe but definitely felt it A LOT! As the years went by the Dilantin was no longer controlling the seizures and eventually switched neuros and ultimately meds. However, TODAY I don't have a lot of memories of the years when I was on Dilantin. There's a lot of gaps. So, yes at leat for me Dilantin definitely caused me some memory problems both during and long term. But, to be honest my memory is not so great these days either and I've opted to take a lot of videos of my daughter since my guess is I'll probably won't remember a whole lot down the road. Also, you have to be careful if your levels go to high and that happened to me once and I was a complete zombie, started to stink (poison coming out of the pores) and waking up with pools of sweat. Had no idea I was even toxic, but thankfully it wasn't going on for too long until I got my levels checked. That's when I changed neuros and went off that med. So, be careful with that.
Unfortunately I think most of the meds cause some memory problems as well as the seizures, but perhaps you can switch meds and maybe you'll have a little better luck with the memory issues. I do think the newer meds are a bit better for the memory stuff. As far as Dilantin my neuro won't even prescribe it anymore and the only way he'll prescibe it to someone is if they're older and have been taking it for years and it's been controlling their seizures with no problems. Other than that, he won't even consider it.
GOOD LUCK!