Screening for Autism: From Watching Milestones to a Formal Diagnosis

There is no medical test — no blood test — for autism spectrum disorder (ASD). Doctors diagnose it by looking at a child's developmental history and behavior, over several steps. Some people are not diagnosed until they are teenagers or adults, and that delay can cost them the early help they need.

Step 1: Developmental monitoring

Monitoring is an active, ongoing watch on how a child grows, and a running conversation between parents and providers about the child's skills. It checks whether the child reaches the usual developmental milestones — skills most children have by a certain age — in playing, learning, speaking, behaving and moving.

• Anyone who cares for the child can take part: parents, grandparents, early childhood educators and other caregivers.
• CDC's "Learn the Signs. Act Early." program offers free tools, including the Milestone Tracker app and short milestone checklists, to help families and providers spot a concern and decide whether more screening is needed.
• At well visits, the doctor or nurse also monitors development — asking questions, or talking and playing with the child.
• Tell the doctor or nurse about family history, including ASD, learning disorders, intellectual disability or attention-deficit/hyperactivity disorder (ADHD).

Step 2: Developmental screening

Screening is a closer, more formal look, and part of some well-child visits even when nobody is worried. The American Academy of Pediatrics (AAP) recommends:

• Screening questionnaires and checklists are research-based, comparing a child with others the same age, and ask about language, movement, thinking, behavior and emotions.
• A doctor, nurse or other professional can screen — in health care, community or school settings — and parents may be asked to fill in a questionnaire.
• Screen outside the set ages if you or the doctor are concerned, if the child is at high risk (for example, a sibling or other relative with ASD), or if behaviors sometimes linked to ASD appear.
• If your child's provider does not screen regularly, you can ask for it.

Timing: ASD can sometimes be detected at 18 months or younger, and by age 2 a diagnosis by an experienced professional can be considered reliable. Yet many children are not diagnosed until much older.

Step 3: Formal evaluation and diagnosis

A screening tool does not diagnose; it shows whether a child is on track or whether a specialist should look closer. If it flags a concern, a formal developmental evaluation may follow:

• done by one or more trained specialists — a developmental pediatrician, child psychologist, speech-language pathologist and/or occupational therapist;
• the specialist may observe the child, give a structured test, and question parents or caregivers or ask them to fill in questionnaires;
• the results lay out the child's strengths and challenges, show whether the child meets criteria for a developmental diagnosis, and whether they need early intervention services;
• sometimes the specialist recommends genetic counseling and testing.

Diagnosing as early as possible helps children get the services and supports they need to reach their full potential.

One diagnosis, formerly three: ASD now covers conditions once diagnosed separately — autistic disorder, pervasive developmental disorder not otherwise specified (PDD-NOS) and Asperger syndrome. A doctor or other provider can help families through the process.

Sources

Based on "Screening for Autism Spectrum Disorder," Centers for Disease Control and Prevention; a work of the United States government in the public domain.