How Is Autism Diagnosed?

The diversity of autism spectrum disorder can make it difficult to correctly diagnose. Sometimes children with ASD are mistakenly diagnosed with a different disorder, like attention-deficit hyperactivity disorder (ADHD) or oppositional defiant disorder (ODD), or they are told that nothing is wrong. Other times kids are diagnosed with autism when they actually aren’t on the spectrum.

First Steps: There are a variety of screeners that pediatricians or other practitioners might employ as a first step to learning if a child might have autism, before beginning a formal evaluation. Some are questionnaires that parents fill out and others are assessments done by clinicians.

If a screener indicates that a child may have autism spectrum disorder, the child should receive a comprehensive evaluation with someone trained in diagnosing autism. This evaluation should include assessment of a child’s behaviors in different settings and within the context of their overall development, and it should incorporate both clinician observation and parent/caregiver interviews. Evaluations will often include autism-symptom specific measures such as:

  • The Autism Diagnostic Observation Schedule, or the ADOS-2. This is a test with different modules to accommodate a range of children. The purpose of the ADOS is to evaluate the social skills and repetitive behaviors the child displays during the test.
  • The Autism Diagnostic Interview-Revised, or the ADI-R. This is a parent interview that gathers information about both current and past behaviors related to autism.

Evaluations should also include information about other areas of a child’s functioning across contexts. Assessing a child’s cognitive, motor, language and adaptive functioning can provide information on the most appropriate treatments and the impact their symptoms are having on their overall functioning. This includes using measures like:

  • The Vineland Adaptive Behavior Scales, Third Edition (VABS-3). This is a parent interview that provides information about a child’s day-to-day functioning in areas of communication, socialization and daily living skills.  
  • Differential Ability Scales, Second Edition (DAS-II) or Mullen Scales of Early Learning (MSEL). These can be used to evaluate cognitive, language and motor functioning.

Even with these tools it is important to be working with a mental health professional who has experience diagnosing people on the autism spectrum.

Read more about diagnosis here.