Bayesian Investor Blog

My understanding of Aspergers/autism (AS) and ADHD suggests to me that they can’t coexist in one personality. I keep coming across reports of people having both, and I’ve been trying to research whether those reports result from mistaken diagnoses or whether I’m missing something. I haven’t found any insightful discussion that addresses this directly. I’ve done some research on ADHD recently which clarified my ideas on this subject.

Both produce social problems due to unusual ways in which their attention works, and both involve unusually focused attention, which produce a good deal of overlap in symptoms. But there are many other features for which the two seem opposites.

ADHD – shifts attention easily and quickly in response to new stimuli
AS – slow to shift attention in response to stimuli

ADHD – seeks adrenaline rush from stimulating/risky situations
AS – avoids being overwhelmed by stimulating/risky situations

ADHD – often pays attention to multiple tasks at once
AS – finds multitasking unusually hard

From answers.com:

ADHD – makes inappropriate comments due to being impulsive but realizes afterward it was inappropriate

AS – makes inappropriate comments due to not knowing better and not understanding social conventions

ADHD – forgets details of daily routines

AS – follows daily routines rigidly

From another source:

Children with ADHD frequently break rules they understand, but defy and dislike. Children with Asperger’s Syndrome like rules, and break the ones they don’t understand. They are ever alert to injustice and unfairness and, unfortunately, these are invariably understood from their own nonnegotiable perspective. Children with ADHD are often oppositional in the service of seeking attention. Children with Asperger’s disorder are oppositional in the service of avoiding something that makes them anxious

With all these traits, there are wide variations in the degree to which anyone has them. But most of what I know suggests that people on one side of the AS/ADHD spectrum with regard to one of these traits are almost always on the same side with respect to the others, or else too close to the middle to classify.

Since many of these traits are poorly observed by those who diagnose them (you don’t observe peoples’ daily routines in a doctor’s office), it’s easy to imagine that widespread mistakes in diagnoses create a false impression that AS and ADHD coexist. Does anyone know of a good analysis that disagrees with my conclusion?

[Update 2010-11-15: I’ve gotten some feedback from people with some ADHD traits who don’t clearly fit the pattern I’ve described. Maybe my analysis only works for one subtype of ADHD, or maybe things are too complex for any existing categories to work as well as I’d like.]