I am this way completely. If I don’t fully understand all the details of something, I have no chance of remembering it. Elementary math classes were difficult in college because they infrequently included formal proofs, but as I progressed into more advanced courses I found I really loved math. The formal proofs made the difference. I need to be convinced that something is true; I can’t simply take it at face value.
ADHD is a disease. You have to go to a doctor to get diagnosed with it. You have to take medicine to be treated for it. It’s studied by medical schools and described in the DSM. It’s genetic and terminal, so the medicine never heals you, unfortunately. It sucks, I know, but it is definitely a disease. No, you can’t “catch” it, but you can’t “catch” Type 1 diabetes either. That is also genetic and terminal.