Screening and Diagnosis of Autism Spectrum Disorder
Diagnosing autism spectrum disorder (ASD) can be difficult because there is no medical test, like a blood test, to diagnose the disorder. Doctors look at the child’s developmental history and behavior to make a diagnosis.
ASD can sometimes be detected at 18 months of age or younger. By age 2, a diagnosis by an experienced professional can be considered reliable . However, many children do not receive a final diagnosis until much older. Some people are not diagnosed until they are adolescents or adults. This delay means that people with ASD might not get the early help they need.
Diagnosing children with ASD as early as possible is important to make sure children receive the services and supports they need to reach their full potential . There are several steps in this process.
Developmental monitoring is an active, ongoing process of watching a child grow and encouraging conversations between parents and providers about a child’s skills and abilities. Developmental monitoring involves observing how your child grows and whether your child meets the typical developmental milestones, or skills that most children reach by a certain age, in playing, learning, speaking, behaving, and moving.
Parents, grandparents, early childhood education providers, and other caregivers can participate in developmental monitoring. CDC’s Learn the Signs. Act Early. program has developed free materials, including CDC’s Milestone Tracker app, to help parents and providers work together to monitor your child’s development and know when there might be a concern and if more screening is needed. You can use a brief checklist of milestones to see how your child is developing. If you notice that your child is not meeting milestones, talk with your doctor or nurse about your concerns and ask about developmental screening. Learn more about CDC Milestone Tracker app, milestone checklists, and other parent materials.
When you take your child to a well visit, your doctor or nurse will also do developmental monitoring. The doctor or nurse might ask you questions about your child’s development or will talk and play with your child to see if they are developing and meeting milestones.
Your doctor or nurse may also ask about your child’s family history. Be sure to let your doctor or nurse know about any conditions that your child’s family members have, including ASD, learning disorders, intellectual disability, or attention deficit/hyperactivity disorder (ADHD).
Developmental screening takes a closer look at how your child is developing.
Developmental screening is more formal than developmental monitoring. It is a regular part of some well-child visits even if there is not a known concern.
The American Academy of Pediatrics (AAP) recommends developmental and behavioral screening for all children during regular well-child visits at these ages:
- 9 months
- 18 months
- 30 months
In addition, AAP recommends that all children be screened specifically for ASD during regular well-child visits at these ages:
- 18 months
- 24 months
Screening questionnaires and checklists are based on research that compares your child to other children of the same age. Questions may ask about language, movement, and thinking skills, as a well as behaviors and emotions. Developmental screening can be done by a doctor or nurse, or other professionals in healthcare, community, or school settings. Your doctor may ask you to complete a questionnaire as part of the screening process. Screening at times other than the recommended ages should be done if you or your doctor have a concern. Additional screening should also be done if a child is at high risk for ASD (for example, having a sibling or other family member with ASD) or if behaviors sometimes associated with ASD are present. If your child’s healthcare provider does not periodically check your child with a developmental screening test, you can ask that it be done.
A brief test using a screening tool does not provide a diagnosis, but it can indicate whether a child is on the right development 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 and is usually done by a trained specialist such as a developmental pediatrician, child psychologist, speech-language pathologist, occupational therapist, or other specialist. The specialist may observe the child give the child a structured test, ask the parents or caregivers questions, or ask them to fill out questionnaires. The results of this formal evaluation highlight your child’s strengths and challenges and can inform whether they meet criteria for a developmental diagnosis.
A diagnosis of ASD now includes several conditions that used to be diagnosed separately; autistic disorder, pervasive developmental disorder not otherwise specified (PDD-NOS), and Asperger syndrome. Your doctor or other healthcare provider can help you understand and navigate the diagnostic process.
The results of a formal developmental evaluation can also inform whether your child needs early intervention services. In some cases, the specialist might recommend genetic counseling and testing for your child.
- Lord C, Risi S, DiLavore PS, Shulman C, Thurm A, Pickles A. Autism from 2 to 9 years of age. Arch Gen Psychiatry. 2006 Jun;63(6):694-701.
- Hyman SL, Levey SE, Myers SM, Council on Children with Disabilities, Section on Developmental and Behavioral Pediatrics. Identification, Evaluation, and Management of Children With Autism Spectrum Disorder. Pediatrics. 2020 Jan;145(1).