daughter on lamictal, can it have cognitive effects?

Hi, i am new to epilepsy.com I have a 12-1/2 year old daughter who seizured in february, 2006. So for a little over a year now we have been on Lamictal. We have not had another seizure since her initial one in feb 2006. Shortly after starting Lamictal, i noticed a huge difference in cara's school work, as did her teachers. Cara had a 98 average last year and was one of the top 10 in her class. Now, she has lack of concentration, grades have fallen considerably and is totally unorganized. She did move from elementary school to middle school in sept, so that too could have an effect. Cara is also a type 1 diabetic since age 4. She is insulin dependant and wears an insulin pump 24/7, and checks her blood glucose about 10-12 times a day depending on afterschool sports and stuff. She is also a fraternal twin. Her twin sister, shannon, is fine, no seizures or diabetes, only freckles!! has anyone else experienced any similiar effects after being on lamictal? if no more seizures accure, we will start to ween her off by february 2007, but she will be getting ready for high school at that time and grades are just not what they used to be. thanks so much for listening! any help is greatly appreciated!