Epilim Chrono (Epilepsy medication) side effects advice?

My brother is on Epilim Chrono controlled release tablets for his epilepsy, and the doctor is advising my parents to reduce the dosage. This is because of a drop in certain things to do with his behavior.

I’ve been told he’s been less enthusiastic towards school work and friends, and sports at school etc.

I want to know if any of you have had experience of this and if you reduced the medication amount because of these side effects. Any advice and information is appreciated.

Thanks