Don't worry. Asperger's syndrome will be removed from DSM-5 next month. So next month, the person won't have the syndrome anymore...The syndrome won't even exist anymore...
So you are saying that almost all studies in social sciences (e.g. psychology) are invalid because almost all of them require participants to voluntarily sign up for the studies.. Also most psychology studies are done with college students, hardly a very representative sample of the population...