Do you really think that there diet has alot to do with this ? They say keep them on a gluten diet well that is hard when they see the rest of the other family members eating ice cream and other things . I always wonder if the brain has something to do with this . Such a crazy disorder never heard this when I grew up but maybe they locked them up in the closet or put them away .
When we were growing up, Asperger syndrome hadn't been "invented yet" and those kids went to regular schools but were misunderstood and didn't fit in. Other kids who would today get classified as autistic used to get categorized as retarded or having a learning disability and wouldn't necessarily be main-streamed.
Anyhow, a GFCF diet is certainly a major undertaking, and you can do a urine test beforehand to see if it would be worthwhile. This test costs around 0 and is probably not covered by insurance. Maybe if you could get your pediatrician to order it? I don't know. We have socialized medicine here in Norway so I don't have to deal with that.
I'm pretty sure my son had this test as part of his evaluation. Normal results.
Here's some information on the test. I have no experience or connection with this lab. There are other labs who do the test, too:
http://www.greatplainslaboratory.com/casein.html
Good luck with everything.