Tony Charman

Prevalence of disorders of the autism spectrum in a population cohort of children in South Thames: the Special Needs and Autism Project (SNAP)

BACKGROUND Recent reports have suggested that the prevalence of autism and related spectrum disorders (ASDs) is substantially higher than previously recognised. We sought to quantify prevalence of ASDs in children in South Thames, UK. METHODS Within a total population cohort of 56 946 children aged 9-10 years, we screened all those with a current clinical diagnosis of ASD (n=255) or those judged to be at risk for being an undetected case (n=1515). A stratified subsample (n=255) received a comprehensive diagnostic assessment, including standardised clinical observation, and parent interview assessments of autistic symptoms, language, and intelligence quotient (IQ). Clinical consensus diagnoses of childhood autism and other ASDs were derived. We used a sample weighting procedure to estimate prevalence. FINDINGS The prevalence of childhood autism was 38.9 per 10,000 (95% CI 29.9-47.8) and that of other ASDs was 77.2 per 10,000 (52.1-102.3), making the total prevalence of all ASDs 116.1 per 10,000 (90.4-141.8). A narrower definition of childhood autism, which combined clinical consensus with instrument criteria for past and current presentation, provided a prevalence of 24.8 per 10,000 (17.6-32.0). The rate of previous local identification was lowest for children of less educated parents. INTERPRETATION Prevalence of autism and related ASDs is substantially greater than previously recognised. Whether the increase is due to better ascertainment, broadening diagnostic criteria, or increased incidence is unclear. Services in health, education, and social care will need to recognise the needs of children with some form of ASD, who constitute 1% of the child population.

Infants with Autism: An Investigation of Empathy, Pretend Play, Joint Attention, and Imitation.

Systematic studies of infants with autism have not been previously carried out. Taking advantage of a new prospective screening instrument for autism in infancy (S. Baron-Cohen et al., 1996), the present study found that, compared with developmentally delayed and normally developing children, 20-month-old children with autism were specifically impaired on some aspects of empathy, joint attention, and imitation. Infants with autism failed to use social gaze in the empathy and joint attention tasks. Both the infants with autism and the infants with developmental delay demonstrated functional play, but very few participants in either group produced spontaneous pretend play. In the developmental delay group, but not the autism group, pretend play was shown following prompting. The implications of these findings for developmental accounts of autism and for the early diagnosis of the disorder are discussed.

A screening instrument for autism at 18 months of age: a 6-year follow-up study

OBJECTIVES A population of 16,235 children aged 18 months was screened using the Checklist for Autism in Toddlers (CHAT) to identify childhood autism (CA). Two further screening procedures were conducted at age 3 and 5 years. The population was followed up at age 7 years in order to establish the sensitivity, specificity, and positive predictive value of the instrument. METHOD A brief checklist assessing joint attention and pretend play behaviors was administered by primary health care practitioners when the children were 18 months old. Follow-up methods included screening through parents and health practitioners and checking medical and educational records. RESULTS Nineteen cases of CA were successfully identified by the CHAT at 18 months. At follow-up a total of 50 cases of CA were identified via all surveillance methods. Thus, the CHAT has a sensitivity of 38% and a specificity of 98% for identifying CA. The positive predictive value of the instrument was maximized by concentration on the highest-risk group. Repeated screening 1 month later increased the positive predictive value to 75% for identification of CA but reduced the sensitivity to 20%, although the specificity was close to 100%. The screen also identified cases of pervasive developmental disorder as well as children with language and other developmental disorders. CONCLUSIONS The CHAT can be used to identify cases of autism and related pervasive developmental disorders at 18 months of age. It is emphasized that the CHAT is not a diagnostic instrument but can identify potential cases of autism spectrum disorders for a full diagnostic assessment.

Autism Spectrum Disorders at 20 and 42 Months of Age: Stability of Clinical and ADI‐R Diagnosis

The association between, and stability of, clinical diagnosis and diagnosis derived from the Autism Diagnostic Interview-Revised (ADI-R; Lord, Rutter, & Le Couteur, 1994) was examined in a sample of prospectively identified children with childhood autism and other pervasive developmental disorders assessed at the age of 20 months and 42 months. Clinical diagnosis of autism was stable, with all children diagnosed with childhood autism at age 20 months receiving a diagnosis of childhood autism or a related pervasive developmental disorder (PDD) at age 42 months. Clinical diagnosis of childhood autism was also reasonably sensitive, with all children who went on to receive a clinical diagnosis of childhood autism at 42 months being identified as having autism or PDD at 20 months. However, clinical diagnosis for PDD and Aspergers syndrome lacked sensitivity at 20 months, with several children who subsequently received these diagnoses at 42 months receiving diagnoses of language disorder or general developmental delay, as well as in two cases being considered clinically normal, at the earlier timepoint. The ADI-R was found to have good specificity but poor sensitivity at detecting childhood autism at 20 months; however, the stability of diagnosis from 20 to 42 months was good. In addition, the ADI-R at age 20 months was not sensitive to the detection of related PDDs or Aspergers syndrome. The continuity and discontinuity between behavioural abnormalities identified at both timepoints in the three domains of impairment in autism was examined, both in children who met final clinical criteria for an autistic spectrum disorder, and for children with language disorder who did not, as well as for a small sample of typically developing children.

Testing joint attention, imitation, and play as infancy precursors to language and theory of mind

Abstract Various theoretical accounts propose that an important developmental relation exists between joint attention, play, and imitation abilities, and later theory of mind ability. However, very little direct empirical evidence supports these claims for putative “precursor” theory of mind status. A small sample ( N =13) of infants, for whom measures of play, joint attention, and imitation had been collected at 20 months of age, was followed-up longitudinally at 44 months and a battery of theory of mind measures was conducted. Language and IQ were measured at both timepoints. Imitation ability at 20 months was longitudinally associated with expressive, but not receptive, language ability at 44 months. In contrast, only the joint attention behaviours of gaze switches between an adult and an active toy and looking to an adult during an ambiguous goal detection task at 20 months were longitudinally associated with theory of mind ability at 44 months. It is argued that joint attention, play, and imitation, and language and theory of mind, might form part of a shared social–communicative representational system in infancy that becomes increasingly specialised and differentiated as development progresses.

Systematic Review of Early Intensive Behavioral Interventions for Children with Autism.

Abstract Recent reviews highlight limitations in the evidence base for early interventions for children with autism. We conducted a systematic review of controlled studies of early intensive behavioral interventions (EIBI) for young children with autism. Eleven studies met inclusion criteria (including two randomized controlled trials). At group level, EIBI resulted in improved outcomes (primarily measured by IQ) compared to comparison groups. At an individual level, however, there was considerable variability in outcome, with some evidence that initial IQ (but not age) was related to progress. This review provides evidence for the effectiveness of EIBI for some, but not all, preschool children with autism.

Parent-mediated communication-focused treatment in children with autism (PACT): a randomised controlled trial

Summary Background Results of small trials suggest that early interventions for social communication are effective for the treatment of autism in children. We therefore investigated the efficacy of such an intervention in a larger trial. Methods Children with core autism (aged 2 years to 4 years and 11 months) were randomly assigned in a one-to-one ratio to a parent-mediated communication-focused (Preschool Autism Communication Trial [PACT]) intervention or treatment as usual at three specialist centres in the UK. Those assigned to PACT were also given treatment as usual. Randomisation was by use of minimisation of probability in the marginal distribution of treatment centre, age (≤42 months or >42 months), and autism severity (Autism Diagnostic Observation Schedule-Generic [ADOS-G] algorithm score 12–17 or 18–24). Primary outcome was severity of autism symptoms (a total score of social communication algorithm items from ADOS-G, higher score indicating greater severity) at 13 months. Complementary secondary outcomes were measures of parent-child interaction, child language, and adaptive functioning in school. Analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN58133827. Results 152 children were recruited. 77 were assigned to PACT (London [n=26], Manchester [n=26], and Newcastle [n=25]); and 75 to treatment as usual (London [n=26], Manchester [n=26], and Newcastle [n=23]). At the 13-month endpoint, the severity of symptoms was reduced by 3·9 points (SD 4·7) on the ADOS-G algorithm in the group assigned to PACT, and 2·9 (3·9) in the group assigned to treatment as usual, representing a between-group effect size of −0·24 (95% CI −0·59 to 0·11), after adjustment for centre, sex, socioeconomic status, age, and verbal and non-verbal abilities. Treatment effect was positive for parental synchronous response to child (1·22, 0·85 to 1·59), child initiations with parent (0·41, 0·08 to 0·74), and for parent-child shared attention (0·33, −0·02 to 0·68). Effects on directly assessed language and adaptive functioning in school were small. Interpretation On the basis of our findings, we cannot recommend the addition of the PACT intervention to treatment as usual for the reduction of autism symptoms; however, a clear benefit was noted for parent-child dyadic social communication. Funding UK Medical Research Council, and UK Department for Children, Schools and Families.

The prevalence of autism spectrum disorders. Recent evidence and future challenges.

Abstract.Background: Until recently best estimate prevalence rates for autism spectrum disorders (ASD) were 0.5/1,000 for autism and 2.0/1,000 for the broader spectrum. Three recent studies have suggested a significantly higher prevalence rate for ASD of 6.0/1,000 (mean 95 % CI = 4.8–8.0). Method: Possible determinants of the apparent increase in the prevalence of ASD are outlined. Methodological aspects of the three recent studies are examined. Findings: Increased recognition, the broadening of the diagnostic concept over time and methodological differences across studies may account for most or all of the apparent increase in prevalence, although this cannot be quantified. Conclusions: Findings from ongoing studies should help confirm or disconfirm the putative rate of 6.0/1,000 for all ASD. The possibility that autism has been over-diagnosed in recent studies needs to be ruled out. Notwithstanding these outstanding questions, it appears likely that the current true prevalence of ASD is considerably greater than previously recognised. This has significant implications for our scientific understanding of ASD and for families and services. Future directions for epidemiological research are outlined.

The Frequency and Distribution of Spontaneous Attention Shifts between Social and Nonsocial Stimuli in Autistic, Typically Developing, and Nonautistic Developmentally Delayed Infants

Spontaneous shifts of attention were observed in autistic, typically developing, and nonautistic developmentally delayed infants. Three types of attention shifting behaviour were observed; (1) between an object and another object, (2) between an object and a person, and (3) between a person and another person. The two control groups shifted attention more frequently between an object and a person than between an object and another object or between a person and another person. The infants with autism showed a different pattern, shifting attention between an object and another object more than any other type of shift. Furthermore, infants with autism showed fewer shifts of attention between an object and a person, and between person and person, than did the two control groups. They also spent less time overall looking at people and looked more briefly at people and for longer durations at objects, compared to the two control groups. These results indicate an abnormality in social orientation in autism even at the early age of 20 months.

ArticlesParent-mediated communication-focused treatment in children with autism (PACT): a randomised controlled trial

Summary Background Results of small trials suggest that early interventions for social communication are effective for the treatment of autism in children. We therefore investigated the efficacy of such an intervention in a larger trial. Methods Children with core autism (aged 2 years to 4 years and 11 months) were randomly assigned in a one-to-one ratio to a parent-mediated communication-focused (Preschool Autism Communication Trial [PACT]) intervention or treatment as usual at three specialist centres in the UK. Those assigned to PACT were also given treatment as usual. Randomisation was by use of minimisation of probability in the marginal distribution of treatment centre, age (≤42 months or >42 months), and autism severity (Autism Diagnostic Observation Schedule-Generic [ADOS-G] algorithm score 12–17 or 18–24). Primary outcome was severity of autism symptoms (a total score of social communication algorithm items from ADOS-G, higher score indicating greater severity) at 13 months. Complementary secondary outcomes were measures of parent-child interaction, child language, and adaptive functioning in school. Analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN58133827. Results 152 children were recruited. 77 were assigned to PACT (London [n=26], Manchester [n=26], and Newcastle [n=25]); and 75 to treatment as usual (London [n=26], Manchester [n=26], and Newcastle [n=23]). At the 13-month endpoint, the severity of symptoms was reduced by 3·9 points (SD 4·7) on the ADOS-G algorithm in the group assigned to PACT, and 2·9 (3·9) in the group assigned to treatment as usual, representing a between-group effect size of −0·24 (95% CI −0·59 to 0·11), after adjustment for centre, sex, socioeconomic status, age, and verbal and non-verbal abilities. Treatment effect was positive for parental synchronous response to child (1·22, 0·85 to 1·59), child initiations with parent (0·41, 0·08 to 0·74), and for parent-child shared attention (0·33, −0·02 to 0·68). Effects on directly assessed language and adaptive functioning in school were small. Interpretation On the basis of our findings, we cannot recommend the addition of the PACT intervention to treatment as usual for the reduction of autism symptoms; however, a clear benefit was noted for parent-child dyadic social communication. Funding UK Medical Research Council, and UK Department for Children, Schools and Families.