Pervasive Developmental Disorders (Autism Spectrum Disorders): Early Screening

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Pervasive Developmental Disorders(Autism
Spectrum Disorders) Early Screening
Diagnostic Assessment

• Laura Grofer Klinger, Ph.D.
• University of Alabama
• Psychology Department
• December 6, 2004

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Development of Screening Instruments for Early
Diagnosis

• The earlier the intervention, the better the
  outcome in terms of language development, IQ, and
  placement in a regular education classroom.
• Increased emphasis on the development of early
  screening instruments that will lead to earlier
  intervention.

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Why is early diagnosis important?

• Most parents suspect that something is wrong by
  18 months and seek medical assistance by 2 years.
• However, most diagnoses are not made until the
  child is 3-4 years of age.
• Earlier identification leads to earlier
  intervention.
• At least 2 years of intervention during preschool
  years leads to
• Increased language development
• Higher IQ
• Placement in a regular education classroom.

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Early Social Impairments in Autism
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Early Developing Social Impairments in Autism
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Diagnostic Process for Parents

• Concerns that may be deaf or have a hearing
  impairment.
• Concerns over their childs lack of language
  development.
• Concerns that they may have done something wrong
  as a parent (e.g., left the child during a trip,
  moved).
• Decision to take the child in for a medical
  test to determine what is wrong.

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Practice Parameters for the Diagnosis and
Evaluation of Autism(Filipek et al., 1999)

• Recommend routine developmental screening by all
  providers at well-child visits.
• ABSOLUTE indications for immediate further
  evaluation (hearing test and autism screen).
• No babbling by 12 months of age.
• No pointing or other gestures by 12 months.
• No single words by 16 months.
• No 2 word spontaneous (not echolalic) phrases by
  24 months.
• ANY loss of ANY language or social skills at ANY
  age.

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Early Screening Instruments

• Checklist for Autism in Toddlers (CHAT)
• Designed to screen for symptoms of autism at 18
  months of age.
• 9 item parent report 5 item observation.
• Developed for primary care settings.
• Low sensitivity (i.e., it misses a lot of
  children).
• Pervasive Developmental Disorders Screening Test
  (PDDST)
• Screen for symptoms from birth to 48 months.
• Brief (25-30 item) parent report checklist.
• Versions for primary care and developmental
  clinic settings.

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Autism Diagnostic Evaluation

• There is no medical test for autism.
• Genetic testing, referral to a neurologist
  recommended
• Diagnosis is based on parent report and clinician
  observations.
• Detailed Parent Interview
• Autism Diagnostic Interview
• Structured Play Session
• Autism Diagnostic Observation Schedule
• Behavioral Rating Scales
• Childhood Autism Rating Scale
• Cognitive Testing
• Speech and Hearing Evaluation

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Issues in Diagnostic Assessment of Pervasive
Developmental Disorder

• Symptom profile changes across the lifespan.
• e.g., joint attention, repetitive interests and
  behaviors.
• Symptom presentation within the context of
  developmental level.
• e.g., pretend play
• Differentiation between the subtypes of Pervasive
  Developmental Disorders.

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Diagnostic Instruments

• Childhood Autism Rating Scale
• Mental age greater than 36 months.
• Not a lifetime diagnosis.
• Developed prior to DSM-IV.
• Screening instrument
• Social Communication Questionnaire

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Autism Diagnostic Interview - Revised

• Mental age greater than 18 months.
• 96 sensitivity, 92 specificity
• Benefits
• Standardized instrument good validity and
  reliability
• Addresses changing symptom profile
• Lifetime history
• Limitations
• Influenced by parent perceptions/agendas
• Over-diagnoses very delayed children.
• No cutoff scores for non-autism PDDs.
• Lengthy interview

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Autism Diagnostic Observation Scale

• Normed on children from 15 months through 40
  years.
• Four different modules.
• 95 sensitivity.
• Benefits
• Standardized instrument with good validity and
  reliability
• Developmentally appropriate observations.
• Limitations
• Parent interview is needed for repetitive/obsessiv
  e behaviors.
• Differentiation between PDDs.
• Current, not life-time diagnosis.

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Autism vs. Mental Retardation

• 40-69 of children with autism have mental
  retardation.
• Both groups show stereotyped behaviors.
• Autism is associated with an uneven pattern of
  skills
• Autism is associated with impairments in social
  interaction and in nonverbal communication.

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Developmental Disorder vs. Developmental Delay
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Giving Feedback and Parent Reactions to the
Diagnosis

• Diagnosis not based on scores but on
  observations.
• Have the parents observe part of the assessment
  to insure that they saw the behaviors you are
  discussing.
• Reduce focus on IQ score.
• Be sure to tell the parents that they didnt
  cause the autism.