EPSDT Care for Kids Newsletter

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EPSDT Care for Kids Newsletter

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Winter 2011
(PDF)

Screening and Diagnosis of Autism Spectrum Disorders

Todd Kopelman, PhD, Scott Lindgren, PhD, and David Wacker, PhD
Center for Disabilities and Development, University of Iowa Children’s Hospital

Basic Facts
Autism Spectrum Disorders (ASDs) are a group of neurodevelopmental disorders characterized by significant impairments in the areas of communication, social interaction, and atypical behaviors. ASDs are four times more common in males than females and can be associated with intellectual impairment and co-occurring medical diagnoses including seizure disorders, anxiety, depression, and attention deficits. Prevalence rates for ASDs have risen substantially over the past two decades, with a recent epidemiological survey identifying a national rate of 1 in 110 children.

Based upon this prevalence rate, it is estimated that approximately 6,500 children in Iowa meet the diagnostic criteria for an ASD. Much of the increase in autism appears to be the result of both improved detection and a broadening of the diagnostic criteria, although other factors that may play a role are currently being explored. Autism is a highly heritable disorder and multiple candidate genes have been implicated. Lifetime costs associated with management have been estimated to exceed $3 million per person with ASD.

Diagnosis of Autism Spectrum Disorders
The primary ASDs are Autistic Disorder (or “autism”), Asperger’s Disorder, and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS). Autistic Disorder or “autism” is defined by qualitative impairments in social interaction, communication, and restricted repetitive and stereotyped patterns of behavior, interests, and activities. Common symptoms include poor eye contact, poor “reading” of social cues, failure to develop peer relationships, lack of social or emotional reciprocity, delayed speech, difficulty sustaining conversation, lack of make-believe play, repetitive motor mannerisms, and rigid adherence to routines.

Asperger’s Disorder is defined by impairments in social interaction and restricted or repetitive patterns of behavior, interests, and activities. Common symptoms include poor “reading” of social cues, failure to develop peer relationships, lack of emotional reciprocity, intense interests or preoccupations, and rigid adherence to routines. Children with Asperger's Syndrome do not show general impairments in language or cognitive development, although specific impairments in pragmatic (social) language and visual-motor skills are common.

The diagnosis of PDD-NOS is appropriate when there is pervasive impairment in the development of reciprocal social interaction associated with impairment in either verbal or nonverbal communication skills or with the presence of stereotyped behavior, interests, and activities, but the criteria are not met for a more specific ASD. This diagnosis is often used when a child shows several symptoms consistent with an ASD, but he or she does not meet the full criteria for either Autistic Disorder or Asperger’s Disorder.

Importance of Early Identification
Although there is currently no cure for ASD, interventions have been identified that can successfully improve functioning for many persons with this diagnosis. The most positive outcomes have been shown to occur when intervention is delivered intensively to young children. The importance of early identification in improving outcomes has resulted in an emphasis on training healthcare providers to accurately identify young children at risk for autism. In 2007, the American Academy of Pediatrics recommended that pediatricians conduct universal screenings using an autism-specific screening instrument at 18- to 24-month appointments.

Screening for Autism
In most cases, autism can be reliably diagnosed as early as 18 months of age. An accurate diagnosis is based on observation of the child’s communication, social interaction, behavior, and developmental level.

Referral for a formal evaluation of autism may be warranted if a parent reports that their child exhibits one or more behavioral red flags:

Early signs or “red flags”
that a child may have an autism spectrum disorder

Little or no eye contact
Poor response to name
Lack of or delay in spoken language
Failure to respond to or initiate joint attention
Failure to imitate caregivers
Lack of interest in other children
Lack of spontaneous or make believe play
Persistent fixation on parts of objects
Unusual motor mannerisms (e.g., hand-flapping, lining up objects)

Several measures have been developed to assist in the screening of ASD in young children. The Modified Checklist for Autism in Toddlers (Robins et al.) is a 23-item screener developed for toddlers between the ages of 16 to 30 months. It usually takes around five minutes for caregivers to complete the M-CHAT and two minutes for a healthcare professional to score the measure. The M-CHAT is currently available in 30 languages, is free, and available for download.

Free online administration and scoring will soon be available online as well. The M-CHAT includes seven critical items that best discriminate children at high risk for autism (these include not taking an interest in other children, not pretending, not using index finger to point, not showing objects to parents, not responding to name when called, not following pointing by adults, and appearing not to hear). A child is considered to have failed the M-CHAT when two or more of these “Best7” critical items are endorsed or if any three or more items are endorsed.

A questionnaire is available to follow up on items endorsed by caregivers. Research using the M-CHAT with the revised Best7 scoring suggests that the instrument has very good sensitivity and specificity.

The Screening Tool for Autism in Toddlers (Stone & Ousley) is intended for use with young children ranging in age from 24 to 35 months. Unlike the M-CHAT, which is designed to be used as a general screener, the STAT was designed to help differentiate toddlers with ASD from toddlers who have already been identified as being at-risk for a developmental disability. The STAT is administered via an observation that involves a fairly brief (20-minute) play-based interaction with the toddler. During this observation, the screener attempts to elicit and observe early social and communicative behaviors in four domains: Play, Directing Attention, Motor Imitation, and Requesting. Research with the STAT indicates that the instrument has good psychometric properties.

Next Steps after Screening
If a young child does not pass an autism screen, a formal evaluation for an autism spectrum disorder may be warranted. This evaluation should include a developmental history, developmental assessment, and direct observations of the child’s communication and social behavior. If local evaluation resources are not available, the Autism Center of Excellence at the University of Iowa Children’s Hospital can assist families in obtaining appropriate evaluation through the Center for Disabilities and Development, Pediatric Psychology, or Child Psychiatry.

References

Stone, W. L. & Ousley, O. Y. (1997). STAT Manual: Screening Tool for Autism in Two-Year-Olds. Unpublished manuscript, Vanderbilt University.
Robins, D., Fein, D., Barton, M., Green, J. (2001). “The Modified- Checklist for Autism in Toddlers (M-CHAT): An initial investigation in the early detection of autism and Pervasive Developmental Disorders.” Journal of Autism and Developmental Disorders, 31(2), 131-144.

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