How Is Autism Diagnosed?

How Is Autism Diagnosed?

Autism spectrum disorder (ASD) describes a specific set of developmental and behavioral problems that affect an individual's behavior, as well as an individual's social and communication skills. A diagnosis of ASD means that your child’s social and communication skills, as well as play skills, are affected in some way.

The problem is, most children with an ASD will learn motor skills on time, which means their parents may not initially notice delays in social and communication skills. But the sooner an ASD is identified and diagnosed, the sooner the treatment can start, which means improved outcomes for many children with ASD.

Every child is unique and has his or her own mix of characteristics, which means that as much as children with ASD share similar characteristics, they also can be very different from each other. In other words, children with ASD will still have different likes and dislikes. For example, some children with ASD may not make any eye contact, while other children may seem to stare, and some may make eye contact from time to time.

However, a diagnosis of ASD means that a child’s development will always look different in three main areas:

  • Social skills
  • Communication skills
  • Behavior

Social Skills

Social difficulties in children with ASD can differ. The following are examples of how a child with an ASD may act in social situations:

  • Doesn’t seem to hear when others talk to him or her
  • Appears disinterested of other people and the world around them
  • Doesn’t like to be held or touched
  • Doesn’t play “pretend” games or imitate others
  • Doesn't often have appropriate facial expressions
  • Doesn't show concern and/or empathy for others
  • Avoids eye contact

Communication Skills

Because children with ASD have difficulties with face recognition and a hard time interpreting social cues, communication issues are common and can vary.

  • A child uses facial expressions that don’t match what he or she is saying
  • Doesn't say single words by 16-months-old
  • Doesn’t understand other people’s facial expressions, gestures or tone of voice
  • Gives unrelated answers to questions
  • Reacts unusually to sounds, sights and smells
  • Uses language incorrectly
  • May lose language or other social milestones, between the ages of 15 and 24 months


Repetitive behaviors are very common in children with ASD. They may appear inflexible and obsessive in their interests and activities.

  • A child rocks their body, spins in circles, or flaps their hands
  • Has obsessive interests
  • Flicks light switches on and off
  • Stares at lights or moving objects
  • Lines up toys or other objects
  • Likes routines and rituals and has difficulty with change

Tests and Diagnosis

From birth to 36-months-old, every child should be screened for developmental milestones during routine visits. When a developmental delay is identified, further testing is required. The doctor should refer your child to a specialist in developmental evaluation and early intervention.

There is no single test that can identify and verify an ASD, but diagnosing takes two steps:

1. Developmental Screening

There are many different developmental screening tools. According to The Centers for Disease Control and Prevention, these are some of them:

  • Ages and Stages Questionnaires (ASQ)
  • Communication and Symbolic Behavior Scales (CSBS)
  • Parents’ Evaluation of Developmental Status (PEDS)
  • Modified Checklist for Autism in Toddlers (M-CHAT)
  • Screening Tool for Autism in Toddlers and Young Children (STAT)
  • Childhood Asperger’s Syndrome Test (CAST)

2. Comprehensive Diagnostic Evaluation

This is the second step of diagnosis. It is a thorough review that may include interviewing the parents and looking at the child’s behavior and development, vision and hearing screening, genetic and neurological testing. Specialists who can do a comprehensive diagnostic evaluation include:

  • Developmental pediatricians
  • Child neurologists
  • Child psychiatrists
  • Child psychologists