An interesting work just arrived: Genius Genes: How Asperger Talents Changed the World, by Michael Fitzgerald and Brendan O'Brien (Autism Asperger Publishing Company, 2007). Chapter 4 features an "examination" of Our Man Jefferson, in support of the hypothesis that he had Asperger's Syndrome. It's an intriguing notion, and not the first effort to diagnose TJ with something that might help to explain both his brilliance and his idiosyncrasies (obsessive-compulsive personality disorder was the last one I heard). Unfortunately the case is not very convincing, as argued by Fitzgerald and O'Brien. They rely almost entirely on Norm Ledgin's 2000 book, Diagnosing Jefferson; when they're not quoting Ledgin, they quote other secondary biographers such as Andrew Burstein or Joseph Ellis. This isn't a problem in and of itself, but citation of comments and descriptions of behavior by friends, visitors, acquaintances, and especially family members - which are abundant and readily available - would have served as a much better basis for any sort of assessment.  Diagnosing someone who has been dead for 200 years is an inherently dicey proposition; the shakiness of the whole idea is only made worse by the fact that the information about Jefferson in Genius Genes is clearly going through a filter of at least two or three people before getting to us. Even so, there are a few passages in Genius Genes that get the little hamster in my head running:

According to Ledgin (2000), Ellis noted that "denial mechanisms" gave Jefferson some guidance and that "interior defenses" protected him from becoming unduly pressed (p. 84).  Ellis maintained that "capsules or compartments" had been "constructed" in Jefferson's "mind or soul" to stop conflicting thoughts from colliding (Ellis, 1997, pp. 88, 149, 174).  Such compartmentalization is common in persons with autism...(67)

That's certainly food for thought. Maybe Fitzgerald and O'Brien are on to Ledgin being on to Ellis being on to something there. On the other hand, Ledgin also claims that Jefferson "drank too much." Anyway, the bottom line is that this is a book written by autism experts about historical figures, not a book written by historians about autism. It brings up an interesting claim, but anyone interested in finding substantial evidence to support this theory will need to do some further work.