Gluten-free and Casein-free diet

What on earth are gluten and casein? Can removing them from my child's diet can really improve the symptoms of autism and Pervasive Developmental Disorder (PDD)?

Gluten and casein are getting a lot of attention in the autism community. Some parents, doctors and researchers say that children have shown mild to dramatic improvements in speech and/or behavior after these substances were removed from their diet.

Gluten and gluten-like proteins are found in wheat and other grains, including oats, rye, barley, bulgar, durum, kamut and spelt, and foods made from those grains. They are also found in food starches, semolina, couscous, malt, some vinegars, soy sauce, flavorings, artificial colors and hydrolyzed vegetable proteins.

Casein is a protein found in milk and products containing milk, such as cheese, butter, yogurt, ice cream, whey and even some brands of margarine. It also may be added to non-milk products such as soy cheese and hot dogs in the form of caseinate.

The theory is that some people with autism and PDD cannot properly digest gluten and casein, which form substances that act like opiates in their bodies. This "drug" substance alters the person's behavior, perceptions, and responses to his environment, according to this theory..

GFCF Diet

Can I expect a big changes? Will I report better behavior or notice big difference?

Please share your opinion about that GFCF Diet . I really want to know how was an effect. I know I could benefit from others experiences.