New Zealand Autism Spectrum Disorder Guideline - Ministry of Health

Part 1: Diagnosis and initial assessment of ASD
1.3 Differential diagnosis of autism and consideration of other
possible conditions
Summary of recommendations
Recommendations:
Grade
Part 1
1.3.1 Differential diagnosis must be covered during diagnostic assessment. C
1.3.2 Differential diagnosis must be thorough and cover all conditions commonly
confused with ASD and those known to coexist with ASD.
1.3.3 Health care professionals must have a good understanding of the different forms
of expression of ASD symptomatology across developmental stages and the
symptomatology of common coexisting and alternative conditions.
C
B
Good Practice Points:
1.3.4 Health care professionals must consult with specialists in areas of diagnostic
overlap when issues are not clear.
1.3.5 Diagnosis of ASD in itself may be sufficient. Attempts to delineate ASD from
Asperger syndrome may not be valid and are not necessary.
1.3.a Early childhood
There is no absolute test for ASD. While this is also true for many other situations, it is essential
for clinicians providing assessment and diagnostic services for children with possible ASD to fully
consider other possible diagnoses (the differential diagnosis) 34 80 (Recommendation 1.3.1).
When a child is being assessed for autism, other diagnoses need to be considered, such as:
• hearing impairment
• auditory processing disorder
• environmental deprivation
• attachment disorder
• specific language disorder
• semantic pragmatic language disorder
• dyspraxia
• intellectual disability
• selective mutism
• mental health disorders, such as attention deficit hyperactivity disorder and
opposition defiant disorder
• conduct disorder in the older child
• abuse, trauma, neglect.
New Zealand Autism Spectrum Disorder Guideline 55