Kratos said:
Agreed, there is no way Dewey could be diagnosed with aspergers syndrome
, I think its pop psychology and viewers assuming Dewey’s gift at being able to play music without any known lessons is a link to some form of autism, despite the two being totally separate medical conditions! Him being in a “special” class won’t have helped things especially to the casual viewer.
It's certainly not the intention of the writers to show Dewey as being autistic in the clinical sense. Sporadically, when his extreme sense of being deprived and neglected is triggered, he becomes so self-absorbed as to become emotionally cut off from others. There are two episodes where his behavior crosses the line into typical autistic isolation from others' feelings:
--Reese Joins the Army I: Dewey's sense of being neglected is triggered by the fact that no one in the family cares that he's going to compete in a music contest. In the scene where he watches Hal writhing on the ground while the cops electroshock him, all Dewey can think of is that Hal won't be able to go to the contest.
--Malcolm's Girlfriend: Dewey finally makes a friend, a boy named Ronnie who has wealthy and generous parents. When Ronnie's mother asks Dewey to help her plan a surprise birthday party for Ronnie, this triggers Dewey's obsession with his own deprivation--he recalls that all his birthdays have been miserable. So he tricks Ronnie's mother into throwing the cowboy-themed party that Dewey has always wanted for himself, even though he knows Ronnie hates cowboys. The exchange that resembles an autistic-type emotional cut-off is:
Ronnie: "You ruined my birthday! I hate you!"
Dewey: "I had two sundaes and four sno-cones!"
In that scene, Dewey is so totally focused on the entirely new experience of having a nice party, that he has no awareness of the fact that he has lost his only friend.
This self-absorption is not autism, since Dewey is by no means incapable of sympathizing with others (he often feels sorry for Hal); what it's intended to show is that Dewey has incurred emotional damage from being brought up in a home where he's been deprived of parental care and of even the most basic amenities--he doesn't even have his own bed.