The Problematic Term ASD: Part 2

Yesterday, I offered some thoughts on the planned use of “ASD” to replace the separate diagnoses of Autistic Disorder (AD), Asperger’s Syndrome (AS), and PDD-NOS from a personal perspective. Today, I’ll talk a bit about why, from a research perpective, this isn’t a very good idea either.

Autism has been, naturally, receiving a great deal of focus in various research communities. But it seems the more questions we tackle, the more crop up. One particularly sticky questions is, “Should Asperger’s and Autistic Disorder be considered: a)variations of the same underlying disorder, b) two disorders on an “autism spectrum” or c) two entirely different disorders?”  Each of those answers has its own supporters who have their own arguments as to why their answer makes the most sense. But, really, we don’t have much of an idea.

The first area of interest is cause. Obviously, no one knows what causes autism, and the answer is likely far more complex than we can even consider at the moment. However, there is a  known genetic component. Based on the fact that AD and AS often appear within the same family (mine and statmom‘s, for example), it seems possible that the two share a common gene. It may be then that environmental factors determine whether the eventual presentation is consistent with an AS or an AD diagnosis. But even this is still unknown.

Another area of interest is anatomy. Are AS brains different from AD ones? This would seem like it would have a quick, easy answer. Scan some brains, take some measurements, and presto, an answer is produced. But reality is more complex than that. The differences between NT brain and autistic ones are proposed to be differences in connections and in transmission of signals. With current technology, we can’t measure these sorts of characteristics in living humans. We can look at post-mortem brains and at animal models, but neither can supply exactly the kind of data needed to hash this question out. Seeing as the differences between AS brains and AD brains, if they exist, are likely far more subtle than those between autistic brains and NT brains, we’re likely looking at an additional two decades of research before we can really begin to answer this question.

And finally, there is the issue of intervention. Do those with an AS diagnosis respond differently to therapies like ABA or Floortime than those with AD? What about in the medication realm? Or diet? This is a question we have the technology to answer, but not the fore-knowledge. Before we can tackle this one we need to make sure we have the right individuals in the right groups, i.e. we need a way to exactly distinguish between AS and AD. And until we know which genes or physiological differences to look for, the best we can do is guess.

The solution to this, is not, however, to combine the two categories until we have a better understanding of the differences. If the two aren’t separated diagnostically, recruitment for research will be further complicated and finding answers will only take longer. The solution might be, instead, to find new ways to distinguish between the “autisms,” ways which the DSM is currently not using. We can separate individuals with an ASD by these criteria, do the reseearch into the differences and similarities between and across categories, and from there, rebuild more meaningful diagnostic categories.  In my next post, I will discuss what these potential distinguishing features could be.