While I'm of the opinion that "curing" ADHD at a young age might be a bad idea [1], ADHD is a genetic difference in the brain that is present from birth. It's not a personality thing. It's not something that happens to you later in life.

1: as someone that got diagnosed in adult age, I am now aware of my talents and shortcomings, and all the things I have struggled with. I keep reading of kids on Ritalin that grow to hate their parents for having put them on medication, quit it, and find themselves completely lost in life. They have no idea how dysfunctional they are. They've never had a chance to experience how debilitating it can be.