The age
and pattern of onset also should be noted for autism spectrum disorder.
Symptoms are typically recognized during the second year of life (12-24 months
of age) but may be seen earlier than 12 months if developmental delays are
severe, or noted later than 24 months if symptoms are more subtle. The pattern
of onset description might include information about early developmental delays
or any losses of social or language skills. Typically, this would occur between
12 and 24 months of age and is distinguished from the rare instances of
developmental regression occurring after at least 2 years of normal
development.
The
behavioral features of autism spectrum disorder first become evident in early
childhood, with some cases presenting a lack of interest in social interaction
in the first year of life. Some children with autism spectrum disorder
experience developmental plateaus or regression, with a gradual or relatively
rapid deterioration in social behaviours or use of language, often during the
first 2 years of life. Such losses are rare in other disorders and may be a
useful "red flag" for autism spectrum disorder. Much more unusual and
warranting more extensive medical investigation are losses of skills beyond
social communication (e.g., loss of self-care, toileting, motor skills) or
those occurring after the second birthday (see also Rett syndrome in the
section "Differential Diagnosis" for this disorder).
First
symptoms of autism spectrum disorder frequently involve delayed language
development, often accompanied by lack of social interest or unusual social
interactions (e.g., pulling individuals by the hand without any attempt to look
at them), odd play patterns (e.g., carrying toys around but never playing with
them), and unusual communication patterns (e.g., knowing the alphabet but not
responding to own name). Deafness may be suspected but is typically ruled out.
During the second year, odd and repetitive behaviours and the absence of
typical play become more apparent. Since many typically developing young
children have strong preferences and enjoy repetition (e.g., eating the same
foods, watching the same video multiple times), distinguishing restricted and
repetitive behaviours that are diagnostic of autism spectrum disorder can be
difficult in preschoolers. The clinical distinction is based on the type,
frequency, and intensity of the behavior (e.g., a child who daily lines up
objects for hours and is very distressed if any item is moved).
Autism
spectrum disorder is not a degenerative disorder, and it is typical for
learning and compensation to continue throughout life. Symptoms are often most
marked in early childhood and early school years, with developmental gains
typical in later childhood in at least some areas (e.g., increased interest in
social interaction). A small proportion of individuals deteriorate
behaviourally during adolescence, whereas most others improve.
Only a
minority of individuals with autism spectrum disorder live and work
independently in adulthood; those who do tend to have superior language and
intellectual abilities and are able to find a niche that matches their special
interests and skills. In general, individuals with lower levels of impairment
may be better able to function independently.
However,
even these individuals may remain socially naive and vulnerable, have
difficulties organizing practical demands without aid, and are prone to anxiety
and depression.
Many
adults report using compensation strategies and coping mechanisms to mask their
difficulties in public but suffer from the stress and effort of maintaining a
socially acceptable facade. Scarcely anything is known about old age in autism
spectrum disorder.
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