While this subject is old the topic is still relevant. My father-in-law was on it and it seemed to help for about six months then they had to add or switch to a stronger med (can't recall the name...no pun intended). My sort of friend who I was getting ready to break all ties with turns out to very likely have early onset Alzheimer's or some form of memory loss and/or dementia and now I just feel bad for him and a little guilty but I didn't understand. I called him Jekyll and Hyde because he changed from happy to angry so frequently in one day. I attributed it to alcohol consumption but realized the day before his doctor's appt. to get his MRI results on a brain scan that he actually forgot an entire conversation we had earlier in the day during which I got rather upset with him for his lack of patience and disinterest in what I had to say even though I would politely listen to the details of his job because I knew he needed someone to listen. He had to reference his phone log to even know we had talked and he was not drunk.
He has epilepsy and has been on Dilantin since he was 13. He is now 59. When I feel up to it I will do some research on Dilantin to see if it causes memory loss or actual dementia. He didn't ask the doctor and the test results were inconclusive.
I feel for anyone suffering any kind of dementia. I feel grateful for what health I do have and to just have the kind of memory loss where I need Google to reference actors names and I can use post it notes and my phone's calendar for things I need to remember.
Nothing ever goes away until it teaches us what we need to know ~ Pema Chodron