A hyperlexic boy* I know (we'll call him Adam) has no friends because he has trouble navigating conversations with his classmates or understanding why they behave the way they do. Yet, in 7th grade, he read Pride and Prejudice and talked intelligently about the thoughts, emotions, and behaviors of the characters. He often has no idea when he annoys or offends others. Yet he is highly empathetic, comforting others when they are upset and trying (clumsily) to defuse fights between family members. He refuses to change his behavior in order to fit in (on those occasions when he's aware he's "sticking out"), but he really wants friends and has admitted to being lonely.
People on the autistic spectrum are supposed to have problems with understanding emotions, empathy, or understanding what human relationships are about. And some autistic people clearly do. But where does this child fit in? How can we say he has problems empathizing when he comforts people when they're sad? How can we say he doesn't get the point of human relationships when he wants a friend--and not just the sort of friend you trade baseball cards with, but the kind you can talk to about anything? How can we say he doesn't understand emotions when he can follow Pride and Prejudice in 7th grade?
The usual reply: "The hallmark of a disorder is that a child's functioning is uneven. He or she may or may not have a problem, depending on the situation, the day, his or her mood, or just plain random chance." You get the same response when you ask: "how can a child who can spend four hours straight doing nothing but playing Final Fantasy VII have an attention deficit disorder?"
There's just no logic in a statement like that. If you want to say that a child is unable to focus his attention, he must be unable to in all situations. If he can focus his attention in some situations, he has a problem, yes, but whatever it is, it's not an problem of focusing attention per se. Similarly, if kids on the autistic spectrum have a faulty theory of mind, say, or an inability to understand other's emotions, this problem shouldn't mysteriously disappear as soon as they're removed from an actual, real-time social situation and able to think about it. Again--the child clearly has a problem, but it can't be a problem of theory of mind or an inability to understand other's emotions. That would be illogical.
But never mind logic. What are we to make of Adam being lumped in with Temple Grandin (author of Thinking in Pictures), Sheldon from the TV show Big Bang Theory, Christopher Boone from The Curious Incident of the Dog in the Nighttime, and possibly autistic savants, as examples of high-functioning ASD? What do all these people have in common, other than the label of "high-functioning autistic spectrum disorder?"
IMO, not much.
Yet studies of ASD--at least, the ones I've seen--battle over "the real" cause of ASD. Is it a mirror neuron system dysfunction? A face-reading disorder traceable to the amygdala and fusiform face area? Perhaps there's a cognitive/attentional component? Could it perhaps be because of physical abnormalities (larger brain size with more neuron growth and less pruning from an early age)?
Part of the problem is that these researchers aren't looking at the spectrum, from autistic savants to Adam, as a spectrum. That's not surprising, since they're not clinicians. All the studies I've seen sort only by IQ. Some really subtle ones might address the issue of whether to include people with Asperger's Syndrome and Pervasive Developmental Disorder (PDD-NOS) alongside classic autism cases--many do. Are we to believe that IQ is the only difference between Adam, who thinks in words, and Temple Grandin, who thinks primarily in pictures? Or between Adam, who understands what friendship is about even if he can't make a friend of his own, and Sheldon from Big Bang Theory, who has no clue?
Anyone familiar with the variety of people in the spectrum can see: people on the autistic spectrum might share some symptoms, but there are many differences in their abilities and disabilities. What it means to have trouble understanding others' behavior seems to differ drastically across the autistic spectrum.
Any differences in cognitive functioning must be based in the brain. So if there are a lot of different cognitive "types" within the autistic spectrum--and there have to be--then there must be a lot of different patterns of brain wiring that cause autistic spectrum disorders. Clearly, autistic spectrum is really a "family" of disorders, each presumably with a different neural and developmental source.
There's an analogy in medicine. All skin diseases that caused whiteness of the skin were once known as "leprosy." Gradually, as we started to figure out their causes, the word "leprosy" came to mean a very specific disorder. "Autism" is like "leprosy." It's currently a catchall term referring to a whole bunch of disorders that--hopefully--is gradually being sorted out. Perhaps one will end up keeping the name "autism." I think we'll get to this point eventually, but it'll be difficult. I'll probably explain why in a future post...
*Hyperlexia is a disorder on the autistic spectrum characterized by early development of technical aspects of language, but late development of figurative and social language. To unpack the jargon--Adam, although a late talker, used to spell out the words "Walt Disney Pictures Presents" with alphabet blocks when he was three years old, and learned to read that same year. During neurological testing in early elementary school, it came out that he didn't understand most metaphors. He used to repeat large numbers of phrases he heard on TV or at home indiscriminately, and often inappropriately. It often turned out that he had no idea what they meant. IIRC, this is a typical pattern of language development for a hyperlexic child.