There have been a few threads on topomax experiences.
Here's one from last year.
Update on me: After taking it for just over 2 1/2 years, I finally couldn't stand the neurological effects and the intense dry mouth. I felt stupid, it was increasingly difficult to put words in the right order, and basic arithmetic seemed slightly beyond my grasp. Although I wasn't suicidal, I did have bizarre thoughts which would have produced bodily injury if I'd carried them out. I really had no intention of hurting myself, but I'd wonder about really stupid actions: would my car float if I drive off the bridge? Would my truck bounce if I drove off the railroad overpass and hit the train going beneath me? I've had a stellar driving record over the last 30 some years, but did have 3 minor fender benders while taking topomax.
I've been off it for about 2 years now and everything is reversed except the damage to my salivary glands. It's better, but not back to normal. The neurologic effects stopped quickly, within 2-3 weeks of stopping the drug.
The weight loss effect is a one shot deal: if you stop the drug and go back on, it doesn't seem to do the same thing. It didn't depress my appetite (I was on a very low dose), but it made me not care so much that I was hungry. When I went off the drug for a while and then back on, it didn't have that effect on me
Mel