This condition was originally described by Hans Asperger in Vienna in 1944. Although Asperger was not aware of Leo Kanner's work on autism, he did use the word autism ("autistic psychopathy") to describe the social deficits he observed in a group of boys. His original description, in German, received little attention in the English-language literature until recent years. In people with Asperger's Syndrome, deficits in social interaction and unusual responses to the environment, similar to those in autism, are observed. Unlike in autism, however, cognitive and communicative development are within the normal or near-normal range in the first years of life, and verbal skills are usually an area of relative strength. Idiosyncratic interests are common and may take the form of an unusual and/or highly circumscribed interest (e.g., in train schedules, snakes, the weather, deep-fry cookers, or telegraph pole insulators). There is some suggestion of an increased incidence of this condition in family members. The validity of this condition, as opposed to high-functioning autism, remains a topic of debate (Szatmari, 1992). Inconsistencies in the way the term has been used and the lack, until quite recently, of recognized official definitions has made it difficult to interpret the research available on this condition. Even now, some clinicians will use the term to refer to persons with autism who have IQs in the normal range, or to adults with autism, or to PDD-NOS; recent official definitions emphasize differences from autism, e.g. in terms of better communication (particularly verbal) skills. It also seems likely that that the condition overlaps, at least in part, with some forms of learning disability, e.g., the syndrome of Nonverbal Learning Disability (Rourke, 1989).
CHILDHOOD DISINTEGRATIVE DISORDER
This rather rare condition was described many years before autism (Heller, 1908) but has only recently been 'officially' recognized. With CDD children develop a condition which resembles autism but only after a relatively prolonged period (usually 2 to 4 years) of clearly normal development (Volkmar, 1994). This condition apparently differs from autism in the pattern of onset, course, and outcome (Volkmar, 1994). Although apparently rare the condition probably has frequently been incorrectly diagnosed.
Both the DSM-IV and ICD-10 provide criteria for this condition. The criteria are rather similar in both, although some differences between the two systems are apparent (see recent publications). The condition develops in children who have previously seemed perfectly normal. Typically language, interest in the social environment, and often toileting and self-care abilities are lost, and there may be a general loss of interest in the environment. The child usually comes to look very 'autistic', i.e., the clinical presentation (but not the history) is then typical of a child with autism.