SCREENING & DIAGNOSIS OF AUTISM

Could my child have autism?

Diagnosis is based on behavior. Autism is characterized by delays in a child's social interaction, language as used in social communication, or symbolic or imaginative play. A possible diagnosis of autism would normally involve these characteristics across a range of situations. For example, a child who is late in speaking her first words but developing normally in all other respects is highly unlikely to have autism.

Delays in communication skills may involve your child responding to noises but not your voice, and not speaking by 18 months of age. There may be an actual decrease in communication skills with time, with previously acquired words no longer being used, or only using one or two word sentences after two years of age. A child may not look at the other person's face when spoken to, and appear uninterested in communicating with others. It may be very difficult to get their attention, or get them to return a smile.

Autism can lead to repetitive behaviors and obsessions with certain objects. Early signs of this may be constant rocking movements or flapping of the hands. Attachments to particular objects and eating only certain foods may appear to be much more intense than with those exhibited by other children.

Emotional outbursts can appear to have no cause and the child may not respond to hugs and reassurances. There can be sensory problems such as extreme sensitivity to touch and sounds, and a tendency not to play with other children. A child may only play with a limited number of toys, and may concentrate on only part of the toy.

Importance of screening & early diagnosis

As autism is a developmental disorder, it is important to minimize the delays in your child's development. Early diagnosis and intervention reduce the impact of autism on a child's life so if you suspect your child may have autism, contact your local autism association, doctor or a pediatrician to begin the diagnosis process.

About half of parents of children with Autism Spectrum Disorder notice their child's unusual behaviors by age 18 months, and about four-fifths notice by age 24 months. As postponing treatment may affect long-term outcome, any of the following signs is reason to have a child evaluated by a specialist without delay:

• No babbling by 12 months
• No gesturing (pointing, waving goodbye, etc.) by 12 months
• No single words by 16 months
• No two-word spontaneous phrases (not including echolalia) by 24 months
•Any loss of any language or social skills, at any age.

The American Academy of Pediatrics recommends that all children be screened for Autism Spectrum Disorder at the 18- and 24-month well-child doctor visits, using autism-specific formal screening tests. In contrast, the UK National Screening Committee recommends against screening for Autism Spectrum Disorder in the general population, because screening tools have not been fully validated and interventions lack sufficient evidence for effectiveness. Screening tools include the Modified Checklist for Autism in Toddlers (M-CHAT), the Early Screening of Autistic Traits Questionnaire, and the First Year Inventory; initial data on M-CHAT and its predecessor CHAT on children aged 18–30 months suggests that it is best used in a clinical setting and that it has low sensitivity (many false-negatives) but good specificity (few false-positives). Screening tools designed for one culture's norms for behaviors like eye contact may be inappropriate for a different culture. Genetic screening for autism is generally still impractical.

standard diagnosis of autism

Diagnosis is based on behavior, not cause or mechanism. Autism is defined in the Diagnostic and Statistical Manual of Mental Disorders as exhibiting at least six symptoms total, including at least two symptoms of qualitative impairment in social interaction, at least one symptom of qualitative impairment in communication, and at least one symptom of restricted and repetitive behavior.

Sample symptoms include lack of social or emotional reciprocity, stereotyped and repetitive use of language or idiosyncratic language, and persistent preoccupation with parts of objects. Onset must be prior to age three years, with delays or abnormal functioning in either social interaction, language as used in social communication, or symbolic or imaginative play. The disturbance must not be better accounted for by Rett Syndrome or childhood disintegrative disorder. ICD-10 uses essentially the same definition. For more information on this, see the chapter on the DSM-IV-TR below.

diagnostic instruments

Several diagnostic instruments are available, apart from the DSM-IV-TR. Two are commonly used in autism research: the Autism Diagnostic Interview-Revised (ADI-R) is a semistructured parent interview, and the Autism Diagnostic Observation Schedule (ADOS) uses observation and interaction with the child. The Childhood Autism Rating Scale (CARS) is used widely in clinical environments to assess severity of autism based on observation of children.

how a diagnosis might occur

A pediatrician commonly performs a preliminary investigation by taking developmental history and physically examining the child. If warranted, diagnosis and evaluations are conducted with help from Autism Spectrum Disorder specialists, observing and assessing cognitive, communication, family, and other factors using standardized tools, and taking into account any associated medical conditions. A differential diagnosis for Autism Spectrum Disorder at this stage might also consider intellectual disability, hearing impairment, and a specific language impairment such as Landau-Kleffner syndrome.

In the UK the National Autism Plan for Children recommends at most 30 weeks from first concern to completed diagnosis and assessment, though few cases are handled that quickly in practice. A 2006 U.S. study found the average age of first evaluation by a qualified professional was 48 months and of formal Autism Spectrum Disorder diagnosis was 61 months, reflecting an average 13-month delay, all far above recommendations.

Clinical genetics evaluations are often done once Autism Spectrum Disorder is diagnosed, particularly when other symptoms already suggest a genetic cause. Although genetic technology allows clinical geneticists to link an estimated 40% of cases to genetic causes, consensus guidelines in the U.S. and UK are limited to high-resolution chromosome and fragile X testing. As new genetic tests are developed several ethical, legal, and social issues will emerge. Commercial availability of tests may precede adequate understanding of how to use test results, given the complexity of autism's genetics. Metabolic and neuroimaging tests are sometimes helpful, but are not routine.

Underdiagnosis & overdiagnosis

Underdiagnosis and overdiagnosis are problems in marginal cases, and much of the recent increase in the number of reported Autism Spectrum Disorder cases is likely due to changes in diagnostic practices. The increasing popularity of drug treatment options and the expansion of benefits has given providers incentives to diagnose Autism Spectrum Disorders, resulting in some overdiagnosis of children with uncertain symptoms. Conversely, the cost of screening and diagnosis and the challenge of obtaining payment can inhibit or delay diagnosis. It is particularly hard to diagnose autism among the visually impaired, partly because some of its diagnostic criteria depend on vision, and partly because autistic symptoms overlap with those of common blindness syndromes.

The symptoms of autism and Autism Spectrum Disorders begin early in childhood but are occasionally missed. Adults may seek retrospective diagnoses to help them or their friends and family understand themselves, to help their employers make adjustments, or in some locations to claim disability living allowances or other benefits.

Official diagnosis of Autism in the DSM-IV-TR

Some of the Pervasive Developmental Disorders are increasingly known as Autism Spectrum Disorders, due to the ongoing debate over classification and diagnosis. There are various diagnostic frameworks for Pervasive Developmental Disorders. By far the most common one is the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).

Autism is defined in section 299.00 of the DSM-IV as:

1. A total of six or more items from (1), (2) and (3), with at least two from (1), and one each from (2) and (3):

1. qualitative impairment in social interaction, as manifested by at least two of the following:

1. marked impairment in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body postures, and gestures to regulate social interaction
2. failure to develop peer relationships appropriate to developmental level
3. a lack of spontaneous seeking to share enjoyment, interests, or achievements with other people (e.g., by a lack of showing, bringing, or pointing out objects of interest)
4. lack of social or emotional reciprocity

2. qualitative impairments in communication as manifested by at least one of the following:
1. delay in, or total lack of, the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gesture or mime)
2. in individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others
3. stereotyped and repetitive use of language or idiosyncratic language
4. lack of varied, spontaneous make-believe play or social imitative play appropriate to developmental level
3. restricted repetitive and stereotyped patterns of behavior, interests, and activities, as manifested by at least one of the following:
1. encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus
2. apparently inflexible adherence to specific, nonfunctional routines or rituals
3. stereotyped and repetitive motor mannerisms (e.g., hand or finger flapping or twisting, or complex whole-body movements)
4. persistent preoccupation with parts of objects

2. Delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years:

1. social interaction
2. language as used in social communication
3. symbolic or imaginative play.

3. The disturbance is not better accounted for by Rett’s Disorder or Childhood Disintegrative Disorder.

These are rules of thumb and may not necessarily apply to all diagnosed autistics.

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