This is a topic that really does hit home: I myself am autistic (PDD)and am obsessive Compulsive.
I have heared many a theory as to why autism occurs, anything from Vaccines to television (watching it at an early age, like 1 or 2) to an off-the-wall idea that autism is the next step in our evolution (homo sapiens autism??).
I am a high functioning autistic, but I have had problems in my life with it and OCD, and only very late in my life did i start to take meds to help.
Autistic people like myself have an unusually engineered brain. Lots of areas are enlarged (Frontal lobes,amygdala, Hippocampus, and cerebellum) while the Corpus Callosum is smaller than in a "normal" brain (May 15 2006 issue of TIME Magazine, page 45). The Autistic brain is heavily overloaded with white matter, called "the Brain's connector Cables" (lbid). "local connections" inside the brain are overnumbered, while "long distance" lines are of short supply (lbid).
I agree with Brannakimi in that just as she values her symptoms, I value my symptoms. I wouldn't have it any other way. It's a sole part of me.
"The Nephilim where in the Earth in those days..." Genesis 6:4