The book below has multiple cases of Autistic children improving their ability to communicate, feel and express emotions, and reduce their symptoms. Much of it has to do with changing their diet and a focused detoxification method.

Healing The Symptoms Known as Autism.

EDIT: 👆 Page 165 talks about how parasites also effect people especially those with Autism. Seems like more and more sources are pointing to Parasites as being a big contributor to our health problems.

Gross, but informative reading : Parasite Pill 2.0