Actually there may be a link.
One of the theories of autism (of which there are admittedly many) is that it is (in some cases) triggered by maternal antibodies when a woman has an autoimmune disease (latent or clinically evident) and is pregnant.
http://sfari.org/news-and-opinion/viewp ... -in-autism
Quote:
The possibility that autoimmune mechanisms are a contributing factor in autism spectrum disorders has been entertained for decades, ever since early studies suggested that individuals with autism have a family history of autoimmune disease1,2.
MS is an autoimmune disease. This theory supports a woman with an autoimmune disease being more likely to have an autistic child.
It is not MS specifically. It is the fact of a maternal autoimmune disease, evidence of a hyped-up maternal immune system capable of making antibodies against some part of the developing fetus's brain.
Autoimmune diseases have always been with us in some degree. And so has autism. Now both are increasing in parallel. It may be that the increase in autoimmune diseases (caused by enviromental factors) is the driving force behind the increase in autism.