A research perspective on (some of) the many components of ASD

Transcription

1 Autism Research Centre Centre for Research in Autism & Education A research perspective on (some of) the many components of ASD Dr Greg Pasco Centre for Research in Autism & Education (CRAE) Institute of Education 5 th November 2010

2 Topics 1. Personal perspective 2. Screening 3. Early profiles & High Risk studies 4. Intervention

3 1. Personal perspective Sources of research output International Meeting for Autism Research (IMFAR) A growing number of autism specific journals: Journal of Autism & Developmental Disorders (JADD) Autism Autism Research Research in Autism Spectrum Disorders Focus on Autism and Other Developmental Disabilities Molecular Autism

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5 Sources of research funding MRC Wellcome Trust Autism Speaks Autistica NIH (US) NIHR (UK) (?) Is there an imbalance towards Causes and Cures as opposed to evaluating good practice in everyday clinical provision early identification, diagnosis and treatment?

6 Fred Volkmar 2010 Emanuel Miller lecture at ACAMH:

7 Mike Rutter Presentation at Autism Europe conference, Oct 2010 Genetics: Some associations with rare mutations but lack of specificity for ASD and doubts re. explanatory cause CNVs (esp deletions) 5-10% of ASD cases. Causal? Most CNVs arise de novo and therefore not familial and occur in non-asd individuals Genome-wide association studies (GWAS). Need huge samples, leading to false positives. So far, so unimpressive (Fombonne) Why doesn t autism become extinct? Why haven t susceptibility genes been identified? H 2 = 90%. Similar for other multifactorial conditions. Genetic heterogeneity with small effects for individual genes

8 Screening for autism in toddlers Is it possible? Is it effective? Is it desirable?

9 Screening for autism in toddlers Why? Autism Spectrum Condition (ASC) difficult to detect in very young children Diagnosis of ASC (excluding Asperger syndrome) typically between 3 & 5 years of age, although parental concerns often by 18 months Early identification should lead to early intervention Reduction of stress and increased coping strategies for parents and other family members

10 Is Screening for Autism Desirable? No evidence that screening for autism can reduce the risk of developing the condition Psychological impact for an incorrect screening result Financial cost of screening increased demand for diagnostic services, interventions

11 Early Signs Different developmental trajectories (Rogers, 2004) Retrospective studies: orienting to name, gaze and affect, joint attention Ozonoff et al (2010): no behavioural differences at 6m By 12m - differences in gaze to face and social smiling

12 National Screening - UK Lack of standardised routine developmental screening National Screening Committee examines evidence for: Condition in question Screening test Treatments available Effectiveness of overall screening programme Present policy introduction of [ASD] screening cannot [currently] be recommended (NSC Child Health Subgroup, 2005)

13 Screening Test Terminology Screen + Diagnosis + a True Positives Diagnosis - b False Positives Positive Predictive Value (PPV) = a / a + b Sensitivity = a / a + c (How well does the screen detect cases?) Screen - c False Negatives d True Negatives Specificity = d / b + d (How well does the screen discriminate cases from non-cases?)

14 The CHecklist for Autism in Baron-Cohen et al (1992) Based on: Toddlers (CHAT) Health professional observation (HV, GP) Parental report Expectation that majority of typically developing 18-montholds would show joint attention and pretend play Risk for autism may be revealed by absence of these key behaviours

15 The CHAT Studies Baron-Cohen et al (1992) 18-month-olds (N=41) screened at risk via CHAT By 30 months all high risk infants were diagnosed with an ASD Baird et al (2000) 16,235 children screened and followed up at age 7 PPV high (83%), sensitivity poor (18%) CHAT missed 4 out of 5 children who later received diagnosis Sensitivity improved (38%) when one-stage screening procedure applied, still below acceptable levels

16 Why did the CHAT miss so many cases? Wording has your child ever pointed? Focused primarily on joint attention behaviours and pretend play CHAT screening only took place at 18 months Criteria to determine high and medium risk groups may be too stringent

17 Other screening tools CSBS (Infant Toddler Checklist) Wetherby et al (2009): Community-based sample, n = 5,385. PPV = 0.70, for communication delay including autism (9 to 24-month-olds) Modified-CHAT Kleinman et al (2008): Mixed high risk/low risk sample, n = 3,793. PPV = 0.36, increased to 0.74 when combined with telephone follow-up (16 to 30-month-olds) Screening Tool for Two-year-olds (STAT) Stone et al (2008): High-risk sample, n = 71. PPV = 0.56, for autism (12 to 23-month-olds)

18 Development of the Q-CHAT Parent questionnaire 18m HV check abandoned Q-CHAT Quantitative and Quick 25 items, scored on 5-point scale (0-4) Range of total scores Positive symptoms score more highly Allows for a reduced rate of key behaviours Takes into account the continuum nature of ASC Includes additional items - language development, repetitive and sensory behaviours

19 Sample Item Does your child look at you when you call his/her name? Always -0 Usually -1 Sometimes -2 Rarely -3 Never -4

20 Methods: The Toddler Project 14,000 Q-CHATs sent out to parents of month-olds in 3 PCTs in East of England Returned questionnaires scored and stratified sampling to select children to be assessed: All high scorers ( 44) 50% of high mid-range scorers (41 43) 25% of low mid-range scorers (38 40) ~1% of low scorers ( 37) Took into account missing data in sampling strategy

21 The Toddler Project Assessments: Mostly home visits, within 2-3 months of initial Q- CHAT Child assessments ADOS module 1 (play-based interactive diagnostic) Mullen (verbal and nonverbal IQ) Parent interviews ADI-R (diagnostic) Vineland (adaptive behaviour) Parent-child interaction Repeat Q-CHAT

22 Timetable: The Toddler Project Phase 1: First wave of Q-CHATs sent out in March 2008 So far approx 13,090 sent 3,823 returned (29%) 121 children assessed Phase 2: Follow-up/Confirmation of diagnostic status: Checklist for referral (Has child been referred or diagnosed with any condition since original Q-CHAT?) ADOS, ADI-R, Vinelands, WASI Follow-up assessments (4-5 year olds) by end of 2011

23 Future Directions 1. Examine performance of Q-CHAT in sample enriched with high scorers Child Development Centre 2. Identify best Q-CHAT items and develop referral guide for health/social care professionals: HV, GPs, Nursery Staff 3. Engage with local NHS services to discuss implementation and translation of research findings into practice

24 High-risk sib studies Recruitment of babies who have older sibs with ASD enables prospective observation of the emergence of autism (and BAP & typical development) Several studies in North America and one major study (BASIS) in UK longitudinal study involving assessment at 4, 8, 14, 24 & 36m

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26 Emerging findings: High-risk sib studies Recurrence rate may be >25% (depending on definition of ASD) Regression may be less common than suggested by parental report Group differences detectable at 6m, using technological approaches, such as eye tracking, but not until ~12m using observation This approach is clearly important in understanding the pre-history of autism, but may not contribute so much to early identification/screening of low-risk children

27 Early intervention There are now several RCTs of varied early intervention approaches for children with autism EIBI ESDM PACT Not surprisingly, the evidence shows that these interventions have most impact on the skills and behaviours that are targeted by the intervention

28 EIBI Widely-evaluated, with varied findings mostly moderate to large effect sizes gains in IQ scores variable Appears to work best with more able, less autistic children

29 PACT Green et al, (2010) A large (N=150) RCT of a parent-training intervention Strongest TE Weakest/No TE parent-child child behaviour child behaviour child synchrony with parent with researcher in school

30 Overall Little evidence regarding optimal age Intensity tends to increase (short term) effectiveness but risk of burn-out and plateau-ing after first year High intensity parenting programmes no more effective than low-intensity programmes for parents already experiencing stress Briefer, low intensity programmes can be effective and offer access to a woder range of children and families

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