One of the biggest challenges in effectively treating any disorder is, of course, understanding the nature of the disorder. The challenges in treating autism are further exacerbated by the broad spectrum on which it presents. What works on one "end" of the spectrum may not work on the other.
Myomancy: Different Types of Autism: Complex and Essential pointed me to recent research (.pdf file) from Dr. Judith Miles and others at the University of Missouri (Columbia) Autism Center that defines two points on the spectrum - Complex Autism and Essential Autism. From the paper abstract [emphasis is mine]:
Heterogeneity within the autism diagnosis obscures the genetic basis of the disorder and impedes our ability to develop effective treatments. We found that by using two readily available tests, autism can be divided into two subgroups, ‘‘essential autism’’ and ‘‘complex autism,’’ with different outcomes and recurrence risks. Complex autism consists of individuals in whom there is evidence of some abnormality of early morphogenesis, manifested by either significant dysmorphology or microcephaly. The remainder have ‘‘essential autism.’’ Separating essential from complex autism should be the first diagnostic step for children with autism spectrum disorders as it allows better prognostication and counseling. Definition of more homogeneous populations should increase power of research analyses.The paper goes into quite a bit of detail (including all the good statistical analysis ;-), and I'll be the first to admit I had to look up a few of the terms they use (my favorite - etiology), but it is very interesting reading. A lot to think about, and an extensive list of references to follow up with.
On a somewhat related note is Study: No vaccine, autism tie, a news story I found via Google News that discusses Dr. Miles' findings that there is no connection between vaccinations and autism in children (as I'm sure you gathered from the title of the story). According to the story, Dr. Miles is currently conducting research into the effects of thimerosol during pregnancy.
The study involved women with a certain condition who must receive Rh immune globulin shots during pregnancy. Those women are exposed to thimerosal since it is an ingredient in the injections they receive. "We conclude that there is no indication that pregnancies resulting in children with autism were more likely to be complicated by Rh immune globulin/thimerosal exposure," Miles said.Update
The article in the Rocky Mountain News I mentioned above was a bit light on details and left me curious about Dr. Miles' actual research on the subject. While a quick Google search didn't turn up anything on that front, I found an overview of autism written by Dr. Miles on Gene Tests, a "publicly funded medical genetics information resource developed for physicians, other healthcare providers, and researchers, available at no cost to all interested persons."
The overview is quite detailed, though it does give a broadbrush discussion of causes. All in all, though, worthwhile.