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  • Writer's pictureSharon Starkey

Diagnosing Children with Autism

Have you ever wondered what goes into diagnosing children with autism?

Early identification of children creates dramatically different (better) outcomes for individuals with autism. The earlier a child can be diagnosed, the earlier therapy can begin. They can begin what is called Early Intervention services.

The American Academy of Pediatrics and The National Center of Birth Defects and Developmental Disabilities both recommend that all children be screened for autism. This should be done at nine months, 18 months and 24 months by your pediatrician. The Center for Disease Control has recently rolled out an app to help parents track milestones. (Act Early app)

First Steps

It is difficult to diagnose autism spectrum disorder because there is currently no test to confirm autism such as a blood test. Doctors will need to look at the child’s behavior as well as their developmental history. An experienced professional can sometimes detect autism by the age of 18 months or younger. By the age of two, autism can be reliably detected.

It is also important to involve parents in the screening process. There are many developmental screening tools that can be used for the autism. Some of the most commonly used are:

Ages and Stages Questionnaires (ASQ) This is a general developmental screening tool. It is a parent-completed questionnaire which asks a series of 19 age-specific questions screening communication, gross motor, fine motor, problem-solving, and personal adaptive skills. Results in a pass/fail score for domains.

Communication and Symbolic Behavior Scales (CSBS)

Standardized tool for screening of communication and symbolic abilities up to the 24-month level; the Infant Toddler Checklist is a 1-page, parent-completed screening tool. (CSBS .pdf)

Parents’ Evaluation of Developmental Status (PEDS)

This is a general developmental screening tool. Parent-interview form; screens for developmental and behavioral problems needing further evaluation; single response form used for all ages; may be useful as a surveillance tool.

Modified Checklist for Autism in Toddlers (MCHAT)

Parent-completed questionnaire designed to identify children at risk for autism in the general population. (MCHAT .pdf)

Screening Tool for Autism in Toddlers and Young Children (STAT)

This is an interactive screening tool designed for children when developmental concerns are suspected. It consists of 12 activities assessing play, communication, and imitation skills and takes 20 minutes to administer.

Following screening

Once the developmental screening has been completed, you will be referred to a specialist such as a neuropsychologist, psychiatrist, psychologist, developmental pediatricians or other appropriate specialty, if there are any concerns the child could be on the autism spectrum. At that point, the specialist will want to observe the child’s behavior. This could take place all in the same day or in a series of appointments depending on the provider. The most widely used assessment tools are:

Autism Diagnosis Interview – Revised (ADI-R) (1)

A clinical diagnostic instrument for assessing autism in children and adults. The instrument focuses on behavior in three main areas: reciprocal social interaction; communication and language; and restricted and repetitive, stereotyped interests and behaviors. The ADI-R is appropriate for children and adults with mental ages about 18 months and above.

Autism Diagnostic Observation Schedule – Generic (ADOS-G) (2)

A semi-structured, standardized assessment of social interaction, communication, play, and imaginative use of materials for individuals suspected of having ASD. The observational schedule consists of four 30-minute modules, each designed to be administered to different individuals according to their level of expressive language. (

Childhood Autism Rating Scale (CARS) (3)

Brief assessment suitable for use with any child over 2 years of age. CARS include items drawn from five prominent systems for diagnosing autism; each item covers a particular characteristic, ability, or behavior.

Gilliam Autism Rating Scale – Second Edition (GARS-2) (4)

Assists teachers, parents, and clinicians in identifying and diagnosing autism in individuals ages 3 through 22. It also helps estimate the severity of the child’s disorder.

After all the testing is complete, the scores will be tabulated. This could take a week up to a month or more depending how many evaluations they have scheduled. Finally, the evaluator will sit down with the family and explain the results and recommend resources.


Tadevosyan-Leyfer O, Dowd M, Mankoski R, Winklosky B, Putnam S, McGrath L, et al. A principal components analysis of the Autism Diagnostic Interview–Revised. Journal of the American Academy of Child and Adolescent Psychiatry 2003;42(7):864-872.

Lord C, Risi S, Lambrecht L, Cook EH, Leventhal BL, DiLavore PC, et al. The Autism Diagnostic Observation Schedule–Generic: a standard measure of social and communication deficits associated with the spectrum of autism. Journal of Autism and Developmental Disorders 2000;30(3):205-230.

Van Bourgondien ME, Marcus LM, Schopler E. Comparison of DSM-III-R and Childhood Autism Rating Scale diagnoses of autism. Journal of Autism and Developmental Disorders 1992;22(4):493-506.

Gilliam JE. Gilliam Autism Rating Scale – Second Edition (GARS-2). Austin, TX: Pro-Ed; 1995.


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