A new study by Ruthsatz and Urbach is doing the rounds nowadays. That study has nothing to do with Autism or ADHD per se. The study focuses on child prodigies and finds that they have high levels of intelligence, enhanced working memory and that they pay attention to details.
What the study also found was high level of autistic relatives and high scores on Autism spectrum for the prodigies. The relation between autism and prodigiousness was mediated by the endo-phenotype ‘paying attention to detail’ and none of the other symptoms of ASD seemed to play a role.
Many savants also are high on ASD and have exception working as well as long term memory. There too they pay excessive attention to details and are fascinated by speical interests.
On the other hand there is gathering literature that suggests that the ADHD kid is basically on the creative side of the spectrum – restless, trying multiple strategies, having diffused and peripheral attention, and to an extent novelty and sensation seeking.
Also, if one thinks about that for a minute, autism and ADHD seem to be opposed on a number of dimensions. The three basic features of ADHD are 1) inattentiveness and distractibility vs too much focus and fascination for an object shown by Autistic kid 2) impulsiveness vs restricted and repetitive motions and interests of the autistic kid and finally 3) hyperactivity vs restrained interactions and communications of the autistic kid.
There is also some data from fly models that suggest that autism and ADHD are opposites in a sense.
I may even go ahead and stick my neck and say that while autism is primarily characterized by emotion of Interest/ fascination/ attention ; ADHD is characterized by emotion of Wonder/Awe/surprise.
One theory of autism suggests that the social and communicative difficulties arise as the child hides in a cocoon to prevent over-stimulation and sensory overload; a theory of ADHS says that the child is under-stimulated and needs stimulants like Ritalin to achieve baseline of activation and sensory stimulus.
Another popular theory of autism posits that it arises primarily due to ‘weak central coherence’, or inability to see the context/ gestalt/ ‘the big picture’. The ADHD kid on the other hand is hypothesized to use a lot of peripheral attention and daydreams missing what is being centrally taught in the classroom.
And that brings me to the root of the differences in my opinion; while the Autism spectrum is characterized by a local processing style, the ADHD-psychotic spectrum is characterized by a global processing style.
Some clarifications are due here. I believe ADHD to fall on the psychotic spectrum and have been proposing the autism and psychosis as opposites on a continuum model for close to eternity.
Also, when I say global/local processing styles I dont restrict the application to perception alone, but extend it to include cognitive style too.
There is a lot of work that has been done on global/ local processing styles with respect to perception, using Navon letter tasks and it is fairly established that normally people lean towards the global processing style.
Forrester et al extend this to cover there GLOMOSYS system that posits two basic types of perceptual/cognitive style- global and local.
It is instructive to pause and note here that psychosis is associated with a global processing style while autism with attention to details.
It is also instructive to pause and note that similar to autism-psychosis continuum , it seems Intelligence and creativity are also in a sense opposed to each other. Also while creativity is associated with broad cognitive style that is divergent; intelligence is conceived of as narrow and focused application of abilities.
That brings me to my final analogy: while autistic kids may have pockets of intelligence and savantism and may be driving the evolution of intelligence; it is the ADHD kids who are more likely to be creative and are driving the evolution of creativity.
The romantic notion that psychosis is the price for creativity may not be untrue.
Joanne Ruthsatz, & Jourdan B. Urbach (2012). Child prodigy: A novel cognitive profile places elevated general intelligence,
exceptional working memory and attention to detail at the root
of prodigiousness Intelligence DOI: 10.1016/j.intell.2012.06.002
Jens F¨orster, & Laura Dannenberg (2010). GLOMOsys: A Systems Account of Global Versus Local Processing Psychological Inquiry, DOI: 10.1080/1047840X.2010.487849