A year ago, when my wife and I found out about my son's Autism, we heard that Gluten and Casein can aggravate the condition, and the removal of those proteins from his diet would "cure" him. Without looking into it like the worried, scared parents we were, we tried it. We removed as much as we could from his diet, and waited for any results. Months went by, and nothing changed. His behavior was actually worse, as now he could no longer have is favorite foods (i.e., cottage cheese). So we gave it up as snake oil medicine, and started doing real research.
The diet was made popular by Jenny McCarthy as a method of "treating" her son's Autism, and who declared that Autism "cured". Regardless of the veracity of this declaration, media heavyweights like Oprah have encouraged her and now the method has become a popular tool to "manage" Autism in children. Until recently no one has said one thing against the method, but now the Mayo Clinic has released a study that has blown the method out of the water as a fraud and potentially dangerous for the Autistic child.
Several months back, in my treatise against glutamate as a cause of Autism, I mentioned the gluten-casein connection, what it was, and why it doesn't work for real Autism. Keep in mind that I identify autism as an enlargement of the brain through overgrowth in neurons and therefore increased synapses. I do not identify Autism as a temporary state of behavior, but a prolonged, constant behavior linked to a genetic predisposition for increased brain growth and/or lack of pruning in the brain.
Both gluten and casein are proteins, and in this case molecularly similar proteins. The body metabolizes both proteins into propionic acid, which causes inflammation within the brain if allowed to remain in the blood stream. Most people metabolize the propionic acid into succinyl-CoA through a very long process. A few could have a natural inability to process propionic acid, which could be the cause of Autistic behavior through inflammation to the brain. But it would be temporary, and only occur within regular intervals identified by the ingestion of gluten or casein products (grain or dairy products). So for this particular condition, a gluten and casein free diet would be appropriate.
The problem is, most people seem to believe the hype around this diet as a sure-fire "autism cure" that they place their children on the diet without consulting a doctor. Then, as behavior changes through the placebo effect, they think it's working, and keep it up. The expense is huge, the results minimal for those without the problem of metabolizing propionic acid, and the danger nutritionally to the autistic child is very real.
If you are a parent with an autistic child, please consult a doctor to see if any change of diet would be advisable. Don't try a new and potentially dangerous diet (any diet, for that matter) on the advice of a celebrity. They may be great at their chosen field, but most are not, by any stretch of the imagination, doctors, and therefore are not qualified to give you health advice.