"In your practice, what would you say is the most common symptom shared by children with high functioning autism?"
I would say the most commonly observed symptom in High Functioning Autism involves preoccupation with restricted patterns of interest. Children with High Functioning Autism (HFA) and Asperger’s (AS) are not commonly reported to exhibit ALL of the typical symptoms associated with this disorder…
(e.g., encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus; failure to develop peer relationships appropriate to developmental level; inflexible adherence to specific, nonfunctional routines or rituals; lack of social or emotional reciprocity; lack of spontaneous seeking to share enjoyment, interests, or achievements with other people; marked impairment in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body postures, and gestures to regulate social interaction; persistent preoccupation with parts of objects; stereotyped and repetitive motor mannerisms)
…with the exception of the all-absorbing preoccupation with an unusual and restricted topic, about which vast amounts of factual knowledge are acquired and all too readily demonstrated at the first opportunity in social interaction. Although the actual topic may change from time to time (e.g., every year or so), it may dominate the content of social interchange as well as the activities of HFA and AS children, often immersing the whole family in the subject for long periods of time.
Even though this symptom may not be easily recognized in childhood (because strong interests in dinosaurs or fashionable fictional characters are so common among young kids), it may become more noticeable later on as interests shift to unusual and narrow topics. This behavior is odd in the sense that extraordinary amounts of factual information are learned about very limited topics (e.g., dinosaurs, maps, names of stars, railway schedules, snakes, etc.).
The good news is that the HFA or AS child’s special interest can be used as both a learning and a social skills training tool. More on the topic of “special interests” can be found here: Aspergers Children and Their Special Interests: A Good or Bad Trait?
Online Parent Coaching by Mark Hutten, M.A.