New Zealand Autism Spectrum Disorder Guideline - Ministry of Health

Part 1: Diagnosis and initial assessment of ASD
Part1 Diagnosis and initial assessment of ASD
This section of the ASD Guideline covers the principles of identification,
diagnosis and initial assessment of individuals with ASD.
Part 1
The earlier the diagnosis of ASD is made, the
more impact early intervention has, resulting
in fewer challenging behaviours and better
outcomes for families 17 . For the purposes of
assessment and diagnosis in children, this
guideline divides the population of children into
three age groups, according to developmental
stage and most likely mode of presentation to
services.
• Ages 1 to 3 years – children who present at
this age usually have significant language
delay and behavioural issues. Referral
is usually to a paediatrician, a child
development service or specialised early
intervention service provider.
• Ages 4 to 8 years – children who present
at this age may have milder symptoms of
autism spectrum disorder or may have been
missed for earlier diagnosis.
• Greater than eight years – children who
present at this age usually present to Child,
Adolescent and Family Mental Health
Services with emotional or behavioural
issues. Alternatively, they may present with
school performance difficulties to Special
Education Needs Coordinators (SENCOs),
Resource Teachers of Learning and Behaviour
(RTLBs), Ministry of Education, Special
Education or paediatricians. Occasionally,
they may present via the courts.
Although early intervention may have been
undertaken because of concerns about learning
and development, most children require a
diagnosis to access appropriate management
modalities and support services, and to assist
the family with appropriate information to plan
their lives. It is therefore essential to diagnose
those children with an autism spectrum disorder
early in order to provide early intervention
and family support. International research
demonstrates improved cognitive and functional
outcomes for children who were diagnosed
at younger ages and who then received
appropriate early intervention educational
support 17 . Experienced clinicians are able to
make the diagnosis in children with moderate
to severe ASD by the age of two or three years.
The children with less severe ASD may not come
to attention until they are at early childhood
education services or at school. These children
tend to have better language skills but can still
have significant needs.
Much of the literature on ASD centres on the
early diagnosis and early intervention of young
children with ASD. However, there are also
undiagnosed young people and adults with
ASD. Some seem to manage well 18 19 while other
undiagnosed people and their families endure
great stress, and they can be misunderstood,
blamed, teased, bullied, poorly supported
and miss out on effective treatment options 20 ,
or receive inappropriate medical, psychiatric
and educational interventions. Some receive
psychiatric or intellectual disability services
or both, yet without the recognition of their
ASD, services are not appropriately tailored
to their individual needs (see section 4.8 Mental
health, forensic and disability services). For some
individuals who have not received an ASD
diagnosis, their behaviour may lead to legal
difficulties. Should their difficulties not be
appropriately identified and taken into account
as a mitigating factor, an inappropriate custodial
sentence may result (see section 5.3 Contact with
the justice system).
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New Zealand Autism Spectrum Disorder Guideline