overlap between autism spectrum disorders (ASD)

and specific language impairment (SLI):

diagnostic challenges

Professor Courtenay Frazier NorburyRoyal Holloway

University of London1

why is there so much variation in core language skills within ASD?

2

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

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

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 ASD5

together, these core deficits should really derail language

acquisition

6

‘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

‘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

what is the relationship between autism spectrum disorders and specific language impairment?

9

• 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

verbal and nonverbal communication

reciprocal social interaction

restricted and repetitive

behaviours

core cognitive

deficit

executive function

social understanding

central coherence

ASD

11

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

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)

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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

verbal and nonverbal communication

reciprocal social interaction

restricted and repetitive

behaviours

core cognitive

deficit

executive function

social understanding

central coherence

ASD

15

• 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

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

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

X

19

X

20

21

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

verbal and nonverbal communication

reciprocal social interaction

restricted and repetitive

behaviours

core cognitive

deficit

executive function

social understanding

central coherence

ASD

23

• 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 centralcoherence

24

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

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

weak verbal ability weak CC?

• Snowling & Frith (1986)– performance on

homograph task dependent on language ability in both ASD and Developmental Delay groups

01

23

45

67

89

SLI ALI ALN TD

Group

Faci

liata

tion

diff

eren

ce s

core

27

verbal and nonverbal communication

reciprocal social interaction

restricted and repetitive

behaviours

core cognitive

deficit

executive function

social understanding

central coherence

ASD

28

• 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

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

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

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

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

LI ALI ALN

group

2

4

6

8

10

12

14

16

ADO

S

LI ALI ALN

group

5

10

15

20

25

30

35

Soci

al C

omm

unic

atio

n Q

uest

ionn

aire

(raw

sco

re)

34

Vineland Adaptive Behavior Scales: Socialisation

16th centile

10th centile

3rd centile

LI ALI ALN

60

70

80

90

35

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

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

pre-speech post-speech.0000

.0500

.1000

.1500

.2000

.2500

.3000

.3500

.4000

.4500

typically developing

agentpatientcorebackground

prop

ortio

n fix

ation

pre-speech post-speech.0000

.0500

.1000

.1500

.2000

.2500

.3000

.3500

.4000

.4500

ALN

agentpatientcorebackground

prop

ortio

n fix

ation

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

pre-speech post-speech.0000

.0500

.1000

.1500

.2000

.2500

.3000

.3500

.4000LI

agentpatientcorebackground

prop

ortio

n fix

ation

pre-speech post-speech.0000

.0500

.1000

.1500

.2000

.2500

.3000

.3500

.4000

.4500

ALI

agentpatientcorebackground

prop

ortio

n fix

ation

children with ALI scan the scene differently – they never prioritise looks to the agent!

39

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

so, why is there so much variation in core language skills within the

autism spectrum?

41

• 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

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

trajectories43

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

courtenay.norbury@rhul.ac.uk

www.pc.rhul.ac.uk/sites/lilac 45

Kuhl (2007) model of language

SOCIALNESSSPEECH PROCESSING

perception

phonological skill

computational capacity

??????? amongst many other

things! 46

those who develop good language skills rely on non-social processes

individual differences in non-social processes could explain variation in

language skill...

47

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

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

pro

po

rtio

n o

f fe

atu

res/

ph

on

emes

co

rrec

tly

reca

lled

ASD

TD

49

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

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

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

inhibition

perception

phonological memory

consolidation processes

social engagement

attention control

motor skills

implicitlearning

53

inhibition

perception

phonological memory

consolidation processes

social engagement

attention control

motor skills

implicitlearning

ALN

ALILI

54