48 Chapter 4
speech is often stilted and pedantic, with abnormal intonation; gesturing
may be restricted or exaggerated; and monologues on favourite topics
are easily triggered and hard to stop.
Early aloofness is less likely than in autism. The child with Asperger
syndrome is often interested in other people, although his or her
social interactions are gauche, reflecting impaired empathy and social
responsiveness. In these respects, the individual with Asperger syn-
drome resembles higher-functioning individuals with autism who have
grown out of their aloofness.
Restricted and repetitive behaviours are mostly evident in preoccupa-
tions or circumscribed interests (such as plane spotting or bar codes)
rather than in motor stereotypies such as flapping.
Marked clumsiness may be commoner in Asperger syndrome than in
autism.
While Asperger syndrome is currently distinguished from autism and
‘other’ ASDs, it is unclear whether this distinction really is useful and
whether it should be retained in future.
Associated features of ASDs
Intellectual disability
Many children and adolescents with ASDs also have an intellectual disabil-
ity: in about 40% this is severe (IQ under 50), and in a further 30% this
is mild (IQ 50–69); the remaining 30% have an IQ in the normal range.
In autism, the IQ is generally best measured by non-verbal tests. In severe
autism, verbal IQ is almost always lower than non-verbal IQ because of the
associated language problems. The reverse pattern, with lower non-verbal
than verbal IQ, is common in Asperger syndrome and high-functioning
autism.
Seizures
These affect about a quarter of individuals with autism and intellectual
disability, and about 5% of individuals with autism and normal IQ.
Seizures often begin in adolescence. By contrast, when individuals with
intellectual disability but without autism develop seizures, the onset is
usually in early childhood rather than adolescence.
Other psychiatric problems
In addition to the characteristic features already described, many chil-
dren with autism have additional problems with ADHD, behaviour and
emotions. Parents and teachers commonly complain of over-activity and
poor concentration. A careful history often shows that the ADHD-like
symptoms are evident for tasks such as schoolwork that are imposed
by adults, but not for self-chosen tasks such as lining up toy cars or
watching the same video sequence over and over again. In other instances,