Intellectual ability in WS 04/04/2018. Aims of Lecture. Neurodevelopmental Disorders 2018

Transcription

1 Neurodevelopmental Disorders 2018 Professor Pamela Heaton Session 6 Williams Syndrome Aims of Lecture Intellectual ability Perceptual Processing Executive Functions Social/Emotional Development Language development Williams Syndome has a known genetic basis... Atypical brain development Williams Syndrome Deletion of around 28 genes on chromosome 7q (Tassebehji, 2003) Confirmed using fluorescent in situ hybridizatio (FISH) test Total brain volume decreased by around 13% in WS compared to controls cerebral volume decreased more than cerebellar volume significantly reduced brainstem tissue Deletion of Elastin gene Prevalence = 1 in 7,500 to 1 in 20,000 live births Relative preservation of grey matter and reduction of white matter (connectivity) (Reiss et al., 2000) Intellectual ability in WS Intellectual abilities are typically in the borderline to moderate intellectual disability range (ranging between severe intellectual disability level to average relative to the general population (Martens et al., 2008, Mervis & John, 2010). Williams Syndrome: Moments in Time - YouTube Highest levels of performance on concrete single word identification and production 1

2 Over-friendliness Indiscriminate approach to familiar and unfamiliar faces Rare Condition Makes Little Girl Extremely Friendly - YouTube Social Behaviours in WS WS characterised by hypersociability (never met a stranger) an exaggerated interest to engage in social encounters with both familiar and unfamiliar people (Jawaid et al., 2012) Why might this be? Individuals with WS have significantly increased grey matter volumes in the frontal lobes Is this related to problems with response inhibition and difficulties switching attention (particularly away from faces? Does an exaggerated interest in people reflect difficulties inhibiting strong impulses towards social interaction? - related to Frontal Lobes Highly Uneven Cognitive Profile Peabody Picture Vocabulary Test Expressive Vocabulary Test >80% of children with WS score above 70 on PPVT & EVT 6 8% score at or above 100 Mervis & John, (2010) Williams Syndrome Extremely poor performance on Block Design Test in WS Visual Spatial problems Fastening buttons Climbing stairs IQ profiles and matching in studies Bellugi et al., (1994) - do not show global cohesion (e.g. on Block Design test) Focus on parts not wholes WS show a LOCAL bias in visual perception Similarities with ASD? 2

3 What causes these difficulties in WS? Multifactorial Explanation yr old individuals with WS are poor at encoding Spatial relations between local elements (Farran & Jarrold, 2005) Do not use typical mental rotation strategies (Farran et al, 2001) - Rely on manual manipulation of blocks resulting in slow performance Executive planning? Executive Functions Performance on simple block construction and drawing tasks appear to recruit typical executive planning skills in WS Atypical planning strategies are observed when tasks become more complex Hoffman et al., 2003 Hudson & Farran, 2011 Williams Syndrome TOWERS TASKS Assess planning; working memory... Studies comparing WS and DS on Executive Function Tasks Constanzo (2013) Compared 15 participants with WS (CA = 10 35), 15 participants with DS (CA = 8 21) and 15 TD children (CA = 7.4). Groups matched on mental age Attention, memory, planning, categorization, shifting and inhibition Costanzo (2013) WS & DS showed impairments in auditory sustained attention, visual selective attention, visual categorization and working memory WS were specifically poor in planning. 3

4 Methodological Issues in studying VISUAL SPATIAL SKILLS IN WS Bertrand et al. (1997) Study 1: -Compared children with WS (9-10yrs) to CAmatched and MA-matched controls on object drawing task Study 2: -Compared TD children 4yrs, 5yrs, 6ys, 7yrs on object drawing task Results from study 1 WS produced fewer recognisable drawings than CA matched controls WS included fewer major parts of each object in their drawings than CA matched controls WS drawings were more disorganised than CA matched controls Study 2 BUT Typical 4-yr-olds produced fewer recognisable drawings, with fewer major parts and higher levels of disorganisation than older age groups Developmental delay or atypical trajectory in WS? Children with WS show similarities to TD 4 yr olds = DEVELOPMENTAL DELAY? Children with WS show more serious disorganisation of drawings than TD 4 yr olds = ATYPICAL TRAJECTORY? Visuospatial Processing in WS Dorsal Stream difficulties? Ventral (what) stream = perception Milner & Goodale (1995) Dorsal (where) stream = visual control / action guidance Postbox Task Milner & Goodale, (1995) Task 1: What is the orientation of the slot? VENTRAL TASK Task 2: Post the letter DORSAL Task (Atkinson et al., 1997) On the Postbox task individuals with WS showed relatively less difficulty with the ventral (what) than with dorsal (where) task DORSAL Approached the slot at wrong angle to post the letter Used trial and error to get the letter into slot 4

5 Individuals with WS display impairments on other dorsal stream tasks Mobbs et al. (2007) Meyer-Lindenberg et al. (2004) reduced activation in reduced activation in parietal occipital / parietal cortex cortex Social Development in Williams Syndrome Laing et al., (2002) Investigated jointattention (pre-language skill) during play in toddlers with WS and TD Toys to request Tickle game Turn-taking Posters on the wall Laing et al., (2002) Results Strong relationship between joint attention and language skills (comprehension & production) in both groups TD better at Initiating, requesting and responding to joint attention WS better at dyadic social interaction behaviours Laing et al., (2002) Results For TD participants there were significant correlations between Social interaction & joint attention Social interaction & initiating & requesting Social interaction behaviours less integrated in WS Behaviour mostly dyadic rather than triadic Less interested in objects, more interested in faces? Ideas about the little scientist 5

6 Riby, Hancock, Jones & Hanley (2013) Experimental study comparing 16 participants with WS (aged 8 28 years) and 22 participants with ASD (aged 8 17 years). WS and ASD participants individually matched to TD controls on the basis of non-verbal intelligence. Eye tracking study - participants viewed actors looking at different target objects (e.g. cups, glasses case) in different settings (e.g. office, kitchen, sitting room). Condition 1 (uncued)- spontaneous allocation of attention Condition 2 (cued) detect and name what the actor is looking at Both groups showed atypical interpretation of the socio-cognitive cues but their patterns of performance were very different In uncued condition WS over-attended to faces ASD under-attended to faces In cued condition (what is actor looking at?) WS increased gaze towards correct and incorrect target objects but maintained high engagement with actors face and eyes so were less accurate in identifying objects than controls (sticky fixation) ASD appeared to understand that they needed to follow the actors eye gaze but they did not seem able to do this and looked at the incorrect object WS very interested in faces but how typical is face perception? D Souza et al., (2015) Studied infants with WS (28m), DS (30m) and TD (14m) (all with MA 14m Bayley scale of infant development) Infants familiarized with a schematic face, after which they saw a novel face in which either the configuration of he features or the features themselves (eye shape) were changed 6

7 Configural Change TD infants sensitive to featural and configural change WS only sensitive to featural change Featural Change DS infants looked at both types of stimuli at levels that didn t differ from chance Suggests syndrome specific differences in early face processing Annaz et al., (2009) Investigated partwhole face perception (experimental study) and face recognition (Benton test) in groups with neurodevelopmental disorders Annaz et al., (2009) Experimental Paradigm (A)Whole-face (B) Part-face conditions in upright, 90 orientation and inverted trials Which of the lower stimuli matches the upper (target) face? (Annaz et al., 2009) Recognising faces At around 8 years children with WS performed as well as TD controls (despite showing featural bias on experimental task) Language in Williams Syndrome the general cognitive impairment seen in adolescents and adults with Williams syndrome stands in stark contrast to their relative strength in language, their facility and ease in using sentences with complex syntax, not generally characteristic of other mentally retarded groups (Bellugi, Lichtenberger, Jones, Lai, & St. George, 2000) 7

8 It is theoretically misleading and empirically inaccurate to claim that grammar is spared in WS higher level specialisations such as morphology, syntax, the lexicon and pragmatics are likely to be the emergent product of development rather than its starting state (Karmiloff- Smith, 1992) Methodological issues in WS research Absolute versus Relative Strengths Compared to Visual Spatial skills language is good in WS Methodological issues in WS research Absolute versus Relative Strengths Compared to some other clinical groups language is good in WS No obvious best practise when recruiting control groups Language in WS VIQ over NVIQ advantage seen in WS Driven by exceptionally poor performance on visuo-spatial construction tasks included in non-verbal IQ test battery Speech development Motor difficulties? Masataka (2002) - reported delay in onset of rhythmic hand-banging linked to delay in canonical babbling linked to delay in expressive vocabulary in WS Mervis (2006) delays in vocal development - reduced number of different consonants used - reduced average number of syllables per utterance 8

9 Delays in early language development in WS Delayed expressive language (Mervis et al., (2003) Comprehension and production of referential pointing gestures and engagement in triadic joint attention does not precede the onset of referential expressive language in WS Onset of referential language precedes the onset of pointing by several months (Mervis & Bertrand, 1997) PHONOLOGICAL PROCESSING (CTOPP) 1) Phonological awareness -elision say starfish now say starfish without the fish 2) Sound matching which word starts with the same sound as sock? sun, cake or bear 3) Blending words what word do these sounds make? t-oi Scores on CTOPP in border-line to low average range in WS Correlates with single word reading and non-word reading in WS Levy & Hermon, 2003) Phonological short-term memory Memory for digits 5,2 9,2,4,8,3 Non-word repetition meb teebudieshawlt Higher digit span and non-word rep scores in WS than in DS (e.g. Vicari et al., 2004) - but severe deficits in phonological ST memory in DS WS same (or worse) digit span and nonword rep scores than TD or learning disabled controls matched on receptive vocabulary (e.g. Brock et al., 2002) Phonological memory (nonword repetition) significantly associated with vocabulary in WS (Grant et al., 1997) Morphology Morphological development understanding how the smallest meaningful units of language combine in words WS at/or slightly below the level expected for their overall intellectual abilities (Mervis & Becerra, 2007) Peregrine et al., (2006) study of 6 11 year olds with WS She eats she eat She ate - she eat/ she eated Does the bug want cookies? Is the bug want cookies? Is the bug hungry? Is the bug is hungry Use of intonation rather than grammar to mark a question 9

10 Conceptual difficulties Mervis & John, (2008) Poor performance in 5 7 year olds on Test of Relational Concepts (Edmonston & Litchfield- Thane, 1988) - measures understanding of spatial, quantitative, temporal and dimensional concepts. Score around 30 points lower than on PPVT Mervis & John (2008) 9 11 year olds obtained lowest possible score on the formulated sentences subtest from the CELF. The child is presented with a picture and required to create a sentence using the given word. Very marked difficulties with items tapping understanding of relational concepts items (unless, although) Conceptual difficulties Phillips et al., (2004) Compared 32, 8 38 year olds with WS with learning disabled and TD controls on modified version of the TROG WS more impaired on items tapping spatial and comparative (frog is darker than the hen) concepts Syntax Combining words into phrases understanding the structure of language Bellugi et al., (1988) claims of spared syntactical abilities based on studies that included age and IQ matched adolescents with DS. Abilities in children with WS in line with overall intellectual ability. The chicken on the ball is black Difficulties mapping language onto mental models? Difficulties with complex grammatical constructions (Karmiloff-Smith et al., (1997) Conversational Speech Udwin & Yule (1990) 37% of a sample of children with WS were hyperverbal. Made excessive use of stereotyped phrases, were over-familiar, introduced irrelevant experiences, showed perseverative responding Stojanovik (2006) children with WS poorer at providing information or clarification than children with SLI John et al., (2009) children with WS weakened tendency to communicate their lack of understanding in conversation Children s Communication Checklist (CCC-2 Pragmatics a) speech b) syntax c) inappropriate initiation d) coherence e) stereotyped conversation f) use of context g) rapport h) social relationships i) interests Laws & Bishop (2004) reported significant difficulties in all areas of pragmatics in WS Perform as poorly as children with ASD on scales C and F (Philofsky et al., 2007) 10

11 Evidence from Neuroscience In TD children (>9 yrs) and adults, ERPs show different latency, amplitude and distribution to grammatical function words than to semantic content words Adolescents and adults with WS do not show this difference (eg. St.George, Mills & Bellugi, 2000) Brain activity to language shows normal asymmetries in infancy in WS, but by age 3 4 years atypical pattern seen in children and adults (Mills et al., 2003) WS language system develops along a different trajectory compared to typically developing persons Social Understanding in WS Tager-Flusberg & Sullivan (2000) Investigated social-emotional development in age and IQ matched children with Williams Syndrome & Intellectual handicap using - 1) False belief tasks 2) Explanation of actions task 3) Recognition of emotional expressions Plesa-Skwerer, Faja, Schofield, Verbalis & Tager Flusberg (2006) tested adolescents and adults with WS, age and IQ matched controls (with intellectual impairment) and CA matched TD controls on the faces and paralanguage subtests of the Diagnostic Analysis of Nonverbal Accuracy Scale. WS participants (like IQ matched controls) were impaired on emotion recognition and found negative emotions particularly difficult to distinguish Groups impaired on all tasks Lacroix, Guidetti, Roge & Reilly (2009) Study into identification of emotional facial expression. Compared 12 participants with WS (6 15 years) with 12 participants with Autism (4.9 8 years) (VMA matched) Results showed that recognition of emotional facial expressions was poorer in the WS group than in the Autism group. LINCOLN, SEARCY, JONES & LORD (2007) Compared social behaviour profiles of children with WS and Autism Method: Twenty children with WS (27-58 months) and 26 age- and IQ-equivalent children with AD were administered the Autism Diagnostic Observation Schedule (ADOS). Journal of the American Academy of Child & Adolescent Psychiatry: 2007, 46, (3),

12 Results: Two children with WS met DSM-IV criteria for AD, one of whom was also classified as having AD by the ADOS algorithm. Discriminant analysis of ADOS behaviors indicated that gesture, showing, and quality of social overtures best discriminated the groups. Although some children with WS demonstrated some ASD behaviors, and a minority of children with WS had coexisting AD, the symptom profile in WS was different from AD. Despite some deficits in communication behaviors, showing, and initiating joint attention, children with WS made social overtures and efforts to engage others, whereas children with AD tended not to do so. Summary/Learning outcomes Perception and Executive Functions Hypersociability but atypical and/or delayed social-emotional and language skills. Reading Martens et al, (2008) Review article Riby, Hancock, Jones & Hanley (2013) D Souza et al., (2015) Development of relatively normal/good skills in some individuals in some areas (e.g. vocabulary and face recognition) Proportion of individuals with WS meet criteria for ASD 12