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Prof. Norbury Lecture: 'Overlap between ASD and SLI: diagnostic challenges.

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  • 1. overlap between autism spectrum disorders (ASD) and specific language impairment (SLI): diagnostic challenges Professor Courtenay Frazier Norbury Royal Holloway University of London 1
  • 2. why is there so much variation in core language skills within ASD? 2
  • 3. outline of the session • overview of language profile(s) in ASD • does autism cause language impairment? • is language impairment a co-morbid (co- occurring) condition? • multiple factors that contribute to variation in language development within ASD. 3
  • 4. Language Phonology the sounds of language Syntax/morphology the rules that control sentence formation and word endings (plural, past tense) Semantics the meaning of individual words & words in context Pragmatics the social use of language in context & social exchanges 4
  • 5. autism spectrum disorder (ASD) social-emotional reciprocity nonverbal communicative behaviours developing and maintaining relationships Stereotyped behaviour Routines, rituals & rigidity Highly restricted, fixated interests unusual sensory interests social communication and social interaction restricted repertoire of interests and behaviours DSM-5 criteria for ASD 5
  • 6. together, these core deficits should really derail language acquisition 6
  • 7. ‘normal’ range = omnibus test of language production and comprehension (grammar) = receptive and expressive vocabulary (semantics) = articulation/phonology = non-sense word repetition (memory and phonology) language in ASD is hetergeneous (Tager-Flusberg & Joseph, 2003) 7
  • 8. ‘specific’ language impairment “pragmatic” language skills are extremely variable! structural language impairments are universal deficits in morphosyntax and grammar weaknesses in semantics and word learning limitations in verbal short-term and working memory (poor non-word repetition) 8
  • 9. what is the relationship between autism spectrum disorders and specific language impairment? 9
  • 10. • autism + Language Impairment (ALI) is the outcome of autistic cognition – poor social interaction results in reduced language learning opportunities – weak central coherence impedes learning of language in context • but must explain how some children have an ALN (autism + ‘language normal’) profile SLI Autism ALI A B 10
  • 11. verbal and nonverbal communication reciprocal social interaction restricted and repetitive behaviours core cognitive deficit executive function social understanding central coherence ASD 11
  • 12. autistic symptoms language impairment (standard tests of vocabulary and sentence processing) autism: language ‘normal’ (ALN) autism: language ‘impaired’ (ALI) typically developing (TD) ‘specific’ language impairment (LI) 12
  • 13. autistic symptoms language impairment (standard tests of vocabulary and sentence processing) autism: language ‘normal’ (ALN) autism: language ‘impaired’ (ALI) typically developing (TD) ‘specific’ language impairment (LI) 13
  • 14. direct comparison of language phenotypes… • allows identification of features that are ‘universal’ and ‘specific’ to ASD • allows identification of risk factors that contribute to language impairment (common across disorders) • allows identification of protective factors that facilitate language acquisition, despite ASD 14
  • 15. verbal and nonverbal communication reciprocal social interaction restricted and repetitive behaviours core cognitive deficit executive function social understanding central coherence ASD 15
  • 16. • set of functions necessary for flexible, future-oriented behaviour – working memory – inhibitory control – attentional flexibility – planning • poor executive control could disrupt language learning – difficulties with joint attention – problems inhibiting irrelevant information to the context – problems learning rules – problems planning expressive language executive function 16
  • 17. implications • should be a strong relationship between executive abilities and language competence – discrepant findings regarding correlations between EF tasks and measures of verbal ability • some do: (Pellicano 2007; Liss et al. 2001) • some don’t: (B&N 2005; Landa & Goldberg 2005; Joseph et al. 2005) • different patterns of relationship may depend in part on which measures are used • some studies find associations between poor EF performance and impaired language status, but not ASD status (e.g. Bishop & Norbury 2005; Liss et al. 2001) 17
  • 18. Kelly, Walker & Norbury (2013) Developmental Science • explore eye-movement control in relation to ASD and language impairment • ALI = autism + language impairment • ALN = autism with language ‘normal’ • SLI = specific language impairment • TD = typically developing 18
  • 19. X 19
  • 20. X 20
  • 21. 21
  • 22. challenges • direction of causation is not at all clear: – one alternative explanation is that language important to encode the arbitrary rules needed to succeed on EF tasks (Russell et al. 1999, Zelazo 2004) – another is that EF and language ability are essentially unrelated, but that individuals with ASD fail to use language for self-regulation (Joseph et al. 2005) • relationship between EF and language seen in non-autistic populations (e.g. SLI; Henry et al. 2012) • limited investigation of the developmental relationship between EF and language (especially in ASD) 22
  • 23. verbal and nonverbal communication reciprocal social interaction restricted and repetitive behaviours core cognitive deficit executive function social understanding central coherence ASD 23
  • 24. • tendency to focus on individual, local elements at the expense of global, holistic meaning • explains apparent skill at solving certain visuospatial tasks • could explain disruptions to language because need to integrate different pieces of information in context – joint attention – learning from context weak central coherence 24
  • 25. implications • individuals with ASD, of all ages and abilities, should be impaired at deriving context dependent meaning (Happe 1999) – e.g. homograph task (Happe 1997) • Lucy was cutting onions. In her eye there was a tear. • Lucy was climbing fences. In her dress there was a tear. – inferencing, resolution of ambiguous and figurative expressions 25
  • 26. challenges • problems with verbal coherence are not unique to ASD – seen in virtually every other disorder where language is impaired • good visual spatial skill and poor verbal coherence do not necessarily go together • series of studies demonstrate that weak CC aligns with weak verbal ability, independent of ASD status (Norbury 2004, 2005, Brock et al. 2008) 26
  • 27. weak verbal ability weak CC? • Snowling & Frith (1986) – performance on homograph task dependent on language ability in both ASD and Developmental Delay groups 0 1 2 3 4 5 6 7 8 9 SLI ALI ALN TD Group Faciliatationdifferencescore 27
  • 28. verbal and nonverbal communication reciprocal social interaction restricted and repetitive behaviours core cognitive deficit executive function social understanding central coherence ASD 28
  • 29. • failure to orient to social stimuli early in life: – reduced fixations to faces/eyes – reduced preference for child directed speech • decreased participation in social interactions • poor joint attention – poor gaze following core social deficit poor understanding of social intention / theory of mind disruptions to language learning / pragmatics 29
  • 30. implications • all individuals with ASD should show pervasive language impairments (especially in vocabulary, which relies on use of social cues) • should be strong relationship between measures of “socialness” and measures of language ability • all individuals with ASD should show poor processing of social stimuli, from the earliest ages/stages 30
  • 31. challenges • all individuals with ASD should show pervasive language impairments (especially in vocabulary, which relies on use of social cues) – most do, though ~25 - 43% of cognitively able individuals demonstrate ‘normal’ language skills on standardised tests (Kjelgaard & Tager-Flusberg, 2001; Loucas et al. 2008) – vocabulary often one of the better aspects of language in ASD (Mottron 2004) 31
  • 32. challenges • should be strong correlation between measures of “socialness” and measures of language competence – Kuhl et al. (2005): toddlers with ASD who preferred to listen to non-speech instead of child directed speech • show decreased ability to distinguish different meaningful phonemes • poorer scores on expressive language measures 32
  • 33. Norbury et al. (2009) • Measured symptom severity and social adaptation scores in adolescents with ASD who did and did not have additional language impairments – Social Communication Questionnaire (SCQ) – Autism Diagnostic Observation Schedule (ADOS-Module 4) – Vineland Adaptive Behavior Scales (Socialisation) • Compared scores to adolescents with SLI 33
  • 34. LI ALI ALN group 2 4 6 8 10 12 14 16 ADOS LI ALI ALN group 5 10 15 20 25 30 35 SocialCommunicationQuestionnaire(rawscore) 34
  • 35. Vineland Adaptive Behavior Scales: Socialisation 16th centile 10th centile 3rd centile LI ALI ALN 60 70 80 90 35
  • 36. typically developing adolescents adolescents with autism best social outcome Klin et al. (2002) attention to social stimuli (very high- functioning) Norbury (2009) showed viewing patterns aligned to language status (cf. Rice et al. 2012) 36
  • 37. verbal descriptions of social scenes • children with ASD will look more at background • children with ASD more likely to mention background items in output • children with language impairments (ALI/LI) will produce fewer important sentence elements 37
  • 38. .0000 .0500 .1000 .1500 .2000 .2500 .3000 .3500 .4000 .4500 pre-speech post-speech proportionfixation typically developing agent patient core background .0000 .0500 .1000 .1500 .2000 .2500 .3000 .3500 .4000 .4500 pre-speech post-speech proportionfixation ALN agent patient core background these graphs show the proportion of viewing time to different regions of the screen before and after speakers start their utterance we expect more looks to the agent pre-speech and then a switch to looking more at the patient after they start the utterance 38
  • 39. .0000 .0500 .1000 .1500 .2000 .2500 .3000 .3500 .4000 pre-speech post-speech proportionfixation LI agent patient core background .0000 .0500 .1000 .1500 .2000 .2500 .3000 .3500 .4000 .4500 pre-speech post-speech proportionfixation ALI agent patient core background children with ALI scan the scene differently – they never prioritise looks to the agent! 39
  • 40. the story so far • impaired language development is not causally related to ASD, nor does it account for variation in ASD symptomatology • severity of ASD symptomatology does not fully account for variation in language ability • no one cognitive theory of ASD can explain variation in language phenotype • perhaps language impairments are not caused by autism? 40
  • 41. so, why is there so much variation in core language skills within the autism spectrum? 41
  • 42. • ALI represents the co-morbidity of SLI and ASD – separate causal systems that are themselves correlated. • ALI overlap is due to causal factors for SLI being associated with those causing autism. – same causal factor yielding different diseases (Pleiotropy) • autism and SLI are phenotypic variants of the same set of genes (Bishop, 2003) • should expect overlap in both directions SLI AutismALI A B SLI ALI A B C Autism 42
  • 43. note: partially overlapping disorders ASD involves impairment not seen in SLI (e.g. repetitive interests/behaviours; regression) therefore, would not expect identical patterns of language behaviour, even on tasks both groups find challenging, or remarkably similar developmental trajectories 43
  • 44. the way forward • a truly developmental approach – at risk studies so children are assessed over time • cross disorder and cross cultural comparisons • unified approach to language assessment and characterisation of language impairment • combining behavioural, cognitive, neurobiological evidence in same cohorts • intervention studies to test causal hypotheses 44
  • 45. courtenay.norbury@rhul.ac.uk www.pc.rhul.ac.uk/sites/lilac 45
  • 46. Kuhl (2007) model of language SOCIALNESS SPEECH PROCESSING perception phonological skill computational capacity ??????? amongst many other things! 46
  • 47. those who develop good language skills rely on non-social processes individual differences in non-social processes could explain variation in language skill... 47
  • 48. learned 4 new words (6 exposures to each) • three measures of learning: – recognition – naming (phonology) – defining (semantics) • two time frames: – immediately after learning trials – four weeks later ‘show me the kellow’ 48
  • 49. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Time 1 Time 2 Time 1 Time 2 Semantic Phonological proportionoffeatures/phonemes correctlyrecalled ASD TD 49
  • 50. conclusions from this study • children with ALN very good at learning and retaining phonological information – strong prediction that children with ALI will have additional phonological deficits – may explain facility with text (non-social avenue to word learning?) • unlike peers, children with ALN do not show strong evidence of consolidating learned information (see also Henderson, Gaskell, Powell & Norbury, 2014) – qualitative differences in ASD languagereflect difficulties integrating new information with existing knowledge – underlies difficulties with semantic and pragmatic aspects of meaning? 50
  • 51. ASD (n =13) TD (n = 13) t-value p-value Cohen's d Age (months) 86.46 85.00 1.02 0.32 0.40 Receptive Vocabulary (raw score) 73.54 73.85 0.08 0.93 0.03 Receptive Vocabulary (SS) 100.54 102.31 0.50 0.62 0.20 WASI Matrix Reasoning 51.31 51.77 0.11 0.91 0.05 WASI Definitions 40.00 51.23 3.05 0.006 1.73 can acquire vast store of words despite social limitations clear qualitative differences in what they know about words 51
  • 52. summary • single deficit models of ASD cannot explain the wide variation in language ability that characterises the disorder • risk factors for language impairment are likely to be shared across a number of neuro- developmental disorders • disorder specific risk factors also operate, resulting in rich tapestry of behavioural outcomes 52
  • 53. inhibition perception phonological memory consolidation processes social engagement attention control motor skills implicit learning 53
  • 54. inhibition perception phonological memory consolidation processes social engagement attention control motor skills implicit learning ALN ALI LI 54