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

Autism Spectrum Disorders and

Severe/profound Intellectual disabilities:

Differential Diagnosis

Regional Autism Team: Cork/KerryMay 2014

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.

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)

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.

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

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.

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)

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.

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?

ORReflect the associated ID

and other complex cognitive and language impairments associated with particular syndromes?

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.

• 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, Rett’s, 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.

• 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?

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

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

Identification and assessment of ASD in

individuals with severe/profound ID and/or

genetic syndromes

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.

• 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.

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.

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

Suitable Interview measures individuals with ID

DISCOADI-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)

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.

• Non–verbal 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

Observational measuresADOS: 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

• 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”

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.

- 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.

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