People who don't believe it exists should volunteer with some children who have it. Then you can show us idiots what we're doing wrong.
Or perhaps you might learn something, understand the behaviours and have a little bit more understanding and tact.
We are dealing with Dyspraxia, Autism and ADHD in my house. I would say my daughter is far better behaved than most kids I see. If you saw her having a meltdown in Tescos you'd probably tsk, roll your eyes and judge me for my weak parenting.
Oh and whilst I agree a good diet (which my child has - very little processed food) can help, it's certainly not a "cure"
A lot of these conditions are based in the senses. (Vestibular and proprioceptive specifically) so why judge the parenting of a child that has difficulties processing vestibular stimuli and therefore needs to swing or spin or fidget or run around in order to feel calm in their world.
If you observed my child in class you'd instantly spot her as the "naughty" one. Flitting about, taking books off shelves to look at, pressing her head against the window whilst all the other kids sit, eyes on the teacher, but ask her any question about the days learning and she knows the answer. She's listening and learning, but she has to move to think. Force her to sit on the scratchy carpet is like torture for her, and she won't be able to concentrate. That's the reality of this spectrum of sensory conditions.