I've had epilepsy since 1979 and I found out through personal experience that "long term use" of AEDs can cause a decrease in bone density.
Not sure though how many years are considered to be "long term".
On my request (as a result of info. that I read on this forum) my Neurologist recommended that I take calcium and vitamin D supplements.
The only drawback that I've noticed from the vitamin D among everything else is constipation.
I'm glad that you understand, most ppl don't.
Not much was known about epilepsy back when this all started (1973)
Only known AED drug (that we knew of anyway) was Dilantin.