Early stages of dementia symptoms and conditions

I am a 34 yr old woman who has suffered from migraines for 13 yrs and chronic head pain for most of my life. I have had sinus surgery, my vision checked, TMJ corrected and anything else I could think of to alleviate my headaches. I took various anti-depressants to treat for chronic pain. About 3 yrs ago I began taking Topamax after my grandmother & both my sisters went on it for migraines. We all have experienced success in treating the headaches and both sisters lost weight. Grandmother and I did not. We all still have migraines occasionally and my youngest sister cannot miss a dose w/out having a headache. My grandmother has had to discontinue Topamax because it was effecting her memory, speech, and concentration so badly. All of us experienced the "loss of words" problems at first, but learned to adapt and became used to it. But grandma is in her 70s and its not as easy for her. However, in the past month, I have been experiencing the same thing--memory loss, calling a place or object the wrong name, and poor concentration. I feel like I can't even read today. I was taking 150mg and thought I was pregnant so I started decreasing my dose down to 100mg to wean off. I'm not pregnant and I'm thinking of discontinuing the Topamax anyway. It's bad enough when I can't remember things at home, I can't work like this. I have always raved about how great Topamax is and that if it kept my head from hurting, I would take it forever. Now I feel like I'm in the early stages of dementia.