Autism Spectrum Disorders and Severe/profound Intellectual disabilities: Differential Diagnosis

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Autism Spectrum Disorders and Severe/profound
Intellectual disabilities Differential
Diagnosis

• Regional Autism Team Cork/Kerry
• May 2014

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Session plan

• Following this session I will know more about
• Prevalence of ASD within Severe/Profound ID
  population.
• Genetic syndromes and ASD
• Best practise in identification and assessment of
  ASD in individual with ID and genetic syndromes.

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• Recommended reading
• The assessment and presentation of Autism
  Spectrum Disorder and associated characteristics
  in individuals with severe intellectual
  disability and genetic syndromes
• J.Moss, P. Howlin and C. Oliver. (2011)

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Severe/profound ID Autism Spectrum disorder

• ASD occurs in up to 40 of individuals with
  severe-profound ID levels (La Malfa et al, 2004)
• ASD is more prevalent in individuals with ID
• There is a strong, positive correlation between
  severity of ASD and severity of ID.

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Severe/Profound ID without ASD

• Stereotyped behaviours reported in 67
  individuals with ID (Berkson Davenport, 1962)
• Compulsive behaviours reported in 40 (Bodfish
  et al, 199)
• Large proportion fail to develop communication
  skills
• Do not tend to develop non-verbal communication
  to accommodate

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Reason for the association of ASD and ID?

• The strength of the association has led some
  researcher to believe that there is a shared
  genetic and neurobiological pathway for ASD and
  ID (Abrahams and Gerschwind, 2008)
• Skuse (2008) presence of an ID simply increases
  the risk that ASD will be revealed lower general
  intelligence reduces possibility for cognitive
  compensation for independently determined ASD
  traits.

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Why is a diagnosis important?

• Essential to ensure that individuals receive
  appropriate support and education.
• Behavioural management strategies, educational
  programmes and therapeutic intervention that are
  effective for people with ASD and those without
  may be very different.
• How behaviours are perceived by professional and
  parents/carers (e.g. stubbornness in DS)

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Severe ID Genetic Conditions

• Distinguishing between ASD and the impairments
  and behaviours associated with severe ID becomes
  more difficult in individuals with genetic
  syndromes associated with ID.
• These individual often present with a range of
  complex cognitive, communicative, behavioural,
  emotional and physical difficulties that may mask
  or emulate aspects of ASD or give rise to an
  atypical presentations of the triad of
  impairments.

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Genetic syndromes, ASD and ID

• Identification of ASD in a growing number of
  genetic syndromes- Down Syndrome, Angelman,
  Fragile X, Tuberous Sclerosis

Increase our understanding of genetic/biological
pathways of ASD? OR Reflect
the associated ID and other complex cognitive and
language impairments associated with particular
syndromes?
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Particular Syndromes

• Information on ASD in Fragile X, Down Syndrome,
  Rett's etc are available
• in handouts here today,
• on the Regional website (Regionalasdteam.wordpress
  .com)
• or in the Regional Team Drop box.

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• A number of genetic syndrome reported to show an
  association with ASD is ever growing.
• important to conduct a detailed and fine grained
  assessment of ASD in genetic syndromes- e.g.
  Fragile X, Retts, Cornelia de Lange
• Initial descriptions at a superficial behavioural
  level suggested a significant, even casual,
  relationship with ASD. However, further detailed
  investigation of phenomenology of ASD
  characteristics within their groups reveal a very
  different developmental, behavioural and
  cognitive profile to those found with idiopathic
  ASD.

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• It is helpful to think of these differences as
  unique and syndrome specific signatures of ASD
  phenomenology.
• The fact that the phenomenology of ASD appears to
  differ across genetic syndromes has particular
  implications for the debate regarding the
  boundaries of ASD where do these unusual or
  atypical profiles of ASD sit within the spectrum
  of ASD characteristics?

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• Syndrome specific characterises such as hand
  flapping or excessive sociability in Angelman
  syndrome can be easily misidentified in ASD
  assessments

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In conclusion!

• Need to be EXTEREMLY cautious when assessing
  syndrome groups associated with severe and
  profound ID, as ASD specific assessments and
  indeed diagnostic criteria may not be sensitive
  enough to distinguish between ASD related
  characterises and the effects of the profound ID

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Identification and assessment of ASD in
individuals with severe/profound ID and/or
genetic syndromes
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Difficulties in Assessment

• Significant overlap in the phenomenology of ASD
  and presentation of severe/profound ID
• Both populations have delayed development in
  communication, presence of repetitive behaviours
  and lack of imaginative play skills in addition
  to impairments of social interaction.

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• Some individuals with severe/profound ID may
  appear to fulfil the criteria of the ICD-10 for
  ASD, purely because they have not yet reached the
  developmental level required to acquire these
  behaviours. This is not taken into account in
  current criteria.
• Difficult to identify one single assessment tool
  that is suitable for assessing ASD across the
  whole range of ability and ages in a single
  population.

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What may differentiate ASD from ID alone?

• It has been suggested that some specific forms of
  non-verbal communication are relatively
  unaffected in individual with ID
• Lord and Paul (1997) Individuals with ID show
  significantly more appropriate eye gaze and
  facial expression
• Lord and Pickles (1996) Children with ASD
  develop fewer words and are less likely to
  develop phrase speech than individuals with ID.

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What may differentiate ASD from ID alone?

• Jordon 92001) suggests impairments in
  communication in ID are likely caused primarily
  in acquisition of spoken language. Once
  effective, alternative means of communication are
  introduced, individuals are often able to use
  this alternative mode for a number of functions
  (social and needs) and across settings.
• i.e. they have the motivation to communicate

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Suitable Interview measures individuals with ID

• DISCO
• ADI-R reported agreement of ADI-R and ADOS is
  lower than reported by authors in individuals
  with ID. Ability of the ADI-R to discriminate ASD
  and Severe ID is somewhat limited (Bildt et al,
  2004, Cray 2008)

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Questionnaire measures for individuals with ID

• Social Communication Questionnaire SCQ (Rutter
  et al, 2003)
• Two forms lifetime and current version.
• Discriminate ability of the SCQ is high in
  differentiating ASD from non-autism conditions
  and similarly good for differentiating between
  autism and intellectual disability.
• Validation of SCQ with younger children has
  yielded inconsistent findings.
• Nonverbal individuals are not able to score on 7
  of 39 items. (18). Not suitable for certain
  syndromes (e.g. Angelman)
• Meant as a screening tool

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Observational measures

• ADOS suitable for a range of ages, abilities,
  developmental levels and language skills.
• There has been some concern regarding the
  discriminative ability of the ADOS in children
  with severe ID, the diagnostic validity has been
  reported to be good across a range of ability
  levels (de Bildt et al, 2004).
• The observational nature of the ADOS assessment
  allows for a detailed picture of autistic
  phenomenology provides an opportunity to
  identify some of the subtle behavioural
  characteristics of ASD, enabling better
  differentiation of autistic phenomenology from
  global intellectual disability

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• Recommendation from Moss et al (2011)
• given that the focus of the ADOS is on current
  behaviour it is suggested by the authors that
  this assessment should not be used without an
  accompanying diagnostic interview or screening
  tool to aid diagnosis and clinical judgement

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Combined measures

• Childhood Autism Rating Scale (CARS)
• Schopler et al, 1988.
• Assess the severity of symptoms associated with
  ASD using a short parent/carer interview and
  observation.
• Main disadvantage is that it does not take
  developmental level into account when scoring.
• It is based on the DSM-III criteria it does not
  include items referring to peer relationships,
  joint attention or symbolic play which may be
  important for early diagnosis.

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• Studies have shown that the CARS may be likely to
  misdiagnose young children with ID who DO NOT
  have an ASD.
• Lord (1995) found that the CARS is not sensitive
  enough to diagnose ASD correctly until children
  reach 3 years of age and others report that
  scores on the CARS demonstrate a strong, negative
  correlation with level of IQ and adaptive level
  (Perry et. al, 2005) Therefore it may not be
  suitable for assessing ASD in young children or
  individuals with ID.

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In conclusion!

• Remember standardised assessments are designed to
  AID clinical diagnosis of ASD and they are no
  infallible.
• Use a combination of assessment in addition to
  expert clinical judgement in order to accurately
  identify ASD