Just popping back with another thought. I do agree with Polarbear that parents are desperate to see results, no-one tries a diet like this because it's fun. But honestly it was completely clear in my family that DD#1, DD#3 and I had a salicylate problem and DD#2 & DH did not, and likewise all the other foods that some (or all) of us are now excluding. The diet was painful to do but the answers were really quite clear.
Similarly it is abundantly clear that DD#2 has the classic magic switch response to ADHD medication. There is absolutely no question that it profoundly impacts her functioning. DD#1 possibly there were some mild fuzzy effects, but despite our desperately wanting to help her, it was fairly straightforward to look at the overt change in one and the mild fuzzy possible changes in the other and say "Clearly not the right call for this particularly child to continue with medication, it's not doing anything/enough."
I find it interesting that my child who had the biggest gain from diet had no appreciable gain from medication.
