Diagnosing Autism Spectrum Disorder

From CDC.gov

Diagnosing autism spectrum disorder (ASD) can be difficult because there is no medical test, like a blood test, to diagnose it. Instead, doctors look at the child’s developmental history and behavior to make a diagnosis.

ASD can sometimes be detected at 18 months or younger. By age 2, a diagnosis by an experienced professional can be considered very reliable. However, many children do not receive a final diagnosis until they are older. This delay means they might not get the early intervention therapies they need.

Early signs of ASD can include:

  • Avoiding eye contact,
  • Having little interest in other children or caretakers,
  • Limited display of language (for example, having fewer words than peers or difficulty with use of words for communication), or
  • Getting upset by minor changes in routine.

As children with ASD become adolescents and young adults, they might have difficulties developing and maintaining friendships, communicating with peers and adults, or understanding what behaviors are expected in school or on the job. They may also come to the attention of healthcare providers because they have co-occurring conditions such as attention-deficit/hyperactivity disorder, obsessive compulsive disorder, anxiety or depression, or conduct disorder.

Monitoring, screening, evaluating, and diagnosing children with ASD as early as possible is important to make sure children receive the First Steps early intervention therapies that can help them reach their full potential. There are several steps in this process, which can be found in our Developmental Monitoring and Screening Checklist.

Developmental Monitoring

Developmental monitoring observes how your child grows and changes over time and whether your child meets the typical developmental milestones in playing, learning, speaking, behaving, and moving. Parents, grandparents, early childhood providers, and other caregivers can participate in developmental monitoring. You can use the Autism Spectrum Disorder Indicators Checklist to see how your child is developing. If you notice that your child is not meeting milestones, talk with your doctor about your concerns.

When you take your child to a well visit, your doctor will ask you questions about your child’s development or briefly will talk and play with your child to see if they think your child is developing at the right pace. A missed milestone could be a sign of a problem, so the doctor or another specialist will do a more thorough exam.

Developmental Screening

Developmental screening takes a closer look at how your child is developing. Your child will get a brief test, or you will complete a questionnaire that asks questions about your child’s development, including language, movement, thinking, behavior, and emotions. 

Developmental screening is more formal than developmental monitoring. The American Academy of Pediatrics (AAP) recommends developmental and behavioral screening for all children during their well-child visits at:

  • 9 months
  • 18 months
  • 30 months

In addition, AAP recommends that all children be screened specifically for ASD during regular well-child doctor visits at:

  • 18 months
  • 24 months
  • Additional screening might be needed if a child is at high risk for ASD (e.g., having a family member with an ASD) or if behaviors sometimes associated with ASD are present.

If your child is at higher risk for developmental challenges due to preterm birth, low birthweight, environmental risks like lead exposure or other factors, your healthcare provider may also discuss additional screening. If your child’s healthcare provider does not periodically check your child with a developmental screening test, you can ask that it be done.

Comprehensive Developmental Evaluation

A brief test using a screening tool does not provide a diagnosis, but it indicates if a child is on the right developmental track or if a specialist should take a closer look. If the screening tool identifies an area of concern, a formal developmental evaluation may be needed. This formal evaluation is a more in-depth look at a child’s development, usually by a developmental pediatrician, child psychologist, speech-language pathologist, occupational therapist, or other specialist. This specialist may observe your child, ask you some questions, or have you complete a questionnaire. The results can determine whether your child needs First Steps early intervention services.