Here I share a study from 2012 that I have found through searching more about this subject.
https://pmc.ncbi.nlm.nih.gov/articles/PMC3514756/)
Yesterday, I was at my gastro and came out of this appointment with her very disappointed. She said I am not a specialist in epilepsy and AEDs. Initially, she said she was not aware that AED could cause DAO deficiency, but after making quick searches she found that carbamazepine and topiramate can cause DAO deficiency. Clearly, she did not prepare for this appointment.

She said that Keppra can cause all those gastrointestinal problems I am having and recommended I see a nutritionist to start a diet to hold on better with Keppra and feel a bit better.

Thank you!
Chris (@santosha)