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Biomedical subjects

Tony Charman

Publications and source records attributed to Tony Charman.

At least 19 recordsLinked to original sources
PubMed2007

The Social Communication Assessment for Toddlers with Autism (SCATA): an instrument to measure the frequency, form and function of communication in toddlers with autism spectrum disorder.

The Social Communication Assessment for Toddlers with Autism (SCATA) was designed to measure non-verbal communication, including early and atypical communication, in young children with autism spectrum disorder. Each communicative act is scored according to its form, function, role and complexity. The SCATA was used to measure communicative ability longitudinally in two samples of toddlers with autism spectrum disorder. Overall frequency of non-verbal communicative acts did not change between the two assessments. However, the form and complexity, the function and the role the child took in the interaction did change with time. Both frequency and function of communicative acts in toddlerhood were positively associated with later language ability: social acts, comments and initiations showed greater predictive association than requests and responses.

Autistic Disorder↗
PubMed2006

Adolescent development of motor imagery in a visually guided pointing task.

The development of action representation during adolescence was investigated using a visually guided pointing motor task (VGPT) to test motor imagery. Forty adolescents (24 males; mean age 13.1 years) and 33 adults (15 males; mean age 27.5 years) were instructed to both execute and imagine hand movements from a starting point to a target of varying size. Reaction time (RT) was measured for both Execution (E) and Imagery (I) conditions. There is typically a close association between time taken to execute and image actions in adults because action execution and action simulation rely on overlapping neural circuitry. Further, representations of actions are governed by the same speed-accuracy trade-off as real actions, as expressed by Fitts' Law. In the current study, performance on the VGPT in both adolescents and adults conformed to Fitts' Law in E and I conditions. However, the strength of association between E and I significantly increased with age, reflecting a refinement in action representation between adolescence and adulthood.

Adolescent↗
PubMed2006

Development of action representation during adolescence.

During adolescence the body undergoes many physical changes. These changes necessitate an updating of internal models of action. Here, we tested the hypothesis that internal models undergo refinement between adolescence and adulthood. We investigated the chronometry of executed and imagined hand actions, which relies on internal models, in 40 adolescents (24 males; mean age 13.1 years) and 33 adults (15 males; mean age 27.5 years). In two different motor imagery tasks, the time it took each participant to execute a hand movement was compared with the time it took them to imagine making that movement. For all participants, movement execution time significantly correlated with movement imagery time. However, there was a significant increase in the execution-imagery time correlation between adolescence and adulthood. Cognitive-motor efficiency per se did not change as indexed by both similar execution and imagery times on both tasks for the adolescents and adults. That it was only the correlation between imagined and executed actions that changed with age suggests that the developmental change was specific to generating accurate motor images and not a result of general cognitive improvement with age. The results support the notion that aspects of internal models are refined during adolescence. We suggest that this refinement may be facilitated by the development of parietal cortex during adolescence.

Adolescent↗
PubMed2006

Correlation between clinical severity in patients with Rett syndrome with a p.R168X or p.T158M MECP2 mutation, and the direction and degree of skewing of X-chromosome inactivation.

INTRODUCTION: Rett syndrome (RTT) is an X-linked dominant neurodevelopmental disorder that is usually associated with mutations in the MECP2 gene. The most common mutations in the gene are p.R168X and p.T158M. The influence of X-chromosome inactivation (XCI) on clinical severity in patients with RTT with these mutations was investigated, taking into account the extent and direction of skewing. METHODS: Female patients and their parents were recruited from the UK and Australia. Clinical severity was measured by the Pineda Severity and Kerr profile scores. The degree of XCI and its direction relative to the X chromosome parent of origin were measured in DNA prepared from peripheral blood leucocytes, and allele-specific polymerase chain reaction was used to determine the parental origin of mutation. Combining these, the percentage of cells expected to express the mutant allele was calculated. RESULTS: Linear regression analysis was undertaken for fully informative cases with p.R168X (n = 23) and p.T158M (n = 20) mutations. A statistically significant increase in clinical severity with increase in the proportion of active mutated allele was shown for both the p.R168X and p.T158M mutations. CONCLUSIONS: XCI may vary in neurological and haematological tissues. However, these data are the first to show a relationship between the degree and direction of XCI in leucocytes and clinical severity in RTT, although the clinical utility of this in giving a prognosis for individual patients is unclear.

Amino Acid Substitution↗
PubMed2006

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.

Autistic Disorder↗
PubMed2006

High functioning children with autism spectrum disorder: a novel test of multitasking.

High functioning children with a diagnosis of autism or Asperger's syndrome (HF-ASD) often experience difficulties organising goal-directed actions in their day-to-day lives, requiring support to schedule daily activities. This study aimed to capture these everyday difficulties experimentally using multitasking, a methodology that taps into the cognitive processes necessary for successful goal-directed activities in everyday life. We investigated multitasking in children with HF-ASD using a novel multitask test, the Battersea Multitask Paradigm. Thirty boys participated in the study, 14 with HF-ASD and 16 typically developing controls, matched for age and IQ. Group differences in multitasking were observed. Participants with HF-ASD were less efficient at planning, attempted fewer tasks, switched inflexibly between tasks and broke performance rules more frequently than controls.

Autistic Disorder↗
PubMed2006

Sleep electroencephalograms in young children with autism with and without regression.

A link has been postulated between regressive autism and the spectrum of epileptic encephalopathic conditions including Landau-Kleffner syndrome with the suggestion that subclinical epilepsy may be causative of regression in autism. This is an audit of investigation using sleep electroencephalograms (EEG) in 64 children (56 males, 8 females; mean age 35.6mo [SD 8.2mo]; range 18-48mo) with autism. No child had a history suggestive of epilepsy. Thirty-nine of the children presented with regressive autism and 20 of the participants showed some epileptiform abnormality. There was no significant difference in epileptiform activities in those who showed regression compared with those who did not. No child showed electrical status epilepticus with continuous spike-wave discharges in slow sleep. There was no evidence that these cases of autism with and without regression were associated with epileptic encephalopathy. The significance of epileptiform discharges without epilepsy in the sleep EEG in autism remains unknown.

Autistic Disorder↗
PubMed2005

Gradations of emulation learning in infants' imitation of actions on objects.

This study explored different gradations of emulation in the imitation of actions on objects by 17-month-olds. Experiment 1 established levels of behavioral reproduction following prerecorded video demonstrations similar to those levels following live demonstrations. In Experiment 2, two digitally modified videos, where object movements or body movements critical to producing the target action were highlighted in isolation, were developed. Infants produced the target action equally frequently by observing the object movement video and observing the unmodified video. In contrast, their performance was much less successful based on the body movement video. In Experiment 3, the performance obtained following the object movement video was similar to that following a further video that emphasized the object movements produced in unsuccessful attempts to produce the target action. These findings suggest that emulation in the form of object movement reenactment or affordance learning plays a role in the social learning of actions on objects during infancy.

Attention↗
PubMed2005

Challenges in evaluating psychosocial interventions for Autistic Spectrum Disorders.

In 2002, the National Institutes of Health sponsored a meeting concerning methodological challenges of research in psychosocial interventions in Autism Spectrum Disorders. This paper provides a summary of the presentations and the discussions that occurred during this meeting. Recommendations to federal and private agencies included the need for randomized clinical trials of comprehensive interventions for autism as the highest, but not the sole priority. Ongoing working groups were proposed to address psychosocial interventions with a focus on relevant statistics, standardized documentation and methods of diagnosis, development of outcome measures, establishment of standards in research; and the need for innovative treatment designs, including application of designs from other research areas to the study of interventions in ASD.

Autistic Disorder↗
PubMed2005

Dimensional phenotypic analysis and functional categorisation of mutations reveal novel genotype-phenotype associations in Rett syndrome.

We aimed to improve the understanding of genotype-phenotype correlations in Rett syndrome (RS) by adopting a novel approach to categorising phenotypic dimensions - separating typicality of presentation, outcome severity and age of onset - and by classifying MECP2 mutations strictly by predicted functional attributes. MECP2 mutation screening results were available on 190 patients with a clinical diagnosis of RS (140 cases with classic RS, 50 with atypical RS). 135 cases had identified mutations. Of the 140 patients, 116 with classic RS (82.9%) had an identified mutation compared with 19 of 50 patients (38%) with an atypical presentation. Cases with early onset of regression and seizures, and those with clinical features that might indicate alternative aetiologies, were less likely to have mutations. Individuals with late truncating mutations had a less typical presentation than cases with missense and early truncating mutations, presumably reflecting greater residual function of MECP2 protein. Individuals with early truncating mutations had a more severe outcome than cases with missense and late truncating mutations. These findings held when restricting the analysis to cases over 15 years of age and classic cases only. Previous findings of variation in severity among the common mutations were confirmed. The approach to phenotypic and genotypic classification adopted here allowed us to identify genotype-phenotype associations in RS that may aid our understanding of pathogenesis and also contribute to clinical knowledge on the impact of different types of mutations.

Adolescent↗
PubMed2005

Outcome at 7 years of children diagnosed with autism at age 2: predictive validity of assessments conducted at 2 and 3 years of age and pattern of symptom change over time.

OBJECTIVE: To examine the predictive validity of symptom severity, cognitive and language measures taken at ages 2 and 3 years to outcome at age 7 in a sample of children diagnosed with autism at age 2. METHOD: Twenty-six children diagnosed with autism at age 2 were re-assessed at ages 3 and 7 years. At each age symptom severity, cognitive and language assessments were completed. RESULTS: The pattern of autistic symptom severity varied over time by domain. Across time, children moved across diagnostic boundaries both in terms of clinical diagnosis and in terms of instrument diagnosis on the Autism Diagnostic Interview-Revised (ADI-R). On all measures group variability in scores increased with age. Although non-verbal IQ (NVIQ) for the group as a whole was stable across the 3 assessments, this masked considerable individual instability. Standard assessments at age 2 did not predict outcome at age 7 even within the same domain of functioning. In contrast, standard assessments at age 3 did predict outcome. However, a measure of rate of non-verbal communicative acts taken from an interactive play-based assessment at age 2 was significantly associated with language, communication and social outcomes at age 7. CONCLUSIONS: The trajectory of autism symptoms over time differed in different domains, suggesting that they may be, at least in part, separable. Variability in language, NVIQ and symptom severity increased over time. Caution is required when interpreting the findings from assessments of children with autism at age 2 years. At this age measures of rate of non-verbal communication might be more informative than scores on standard psychometric tests. Predictive validity of assessments at age 3 years was greater.

Adaptation, Psychological↗
PubMed2004

Matching preschool children with autism spectrum disorders and comparison children for language ability: methodological challenges.

Earlier identification of children with autism spectrum disorders (ASDs) is welcome, but presents a number of challenges to the clinical and the research enterprises (see Charman & Baird [2002] for a review). In the research enterprise, one critical methodological challenge is the use of appropriate measures on which to match groups of preschoolers with ASDs to comparison groups with other neurodevelopmental conditions. Language and communication impairments are central to the diagnosis of ASD and, therefore, critical variables to consider in group-matched research designs. In the domain of language function the challenges include the very poor language competence of many preschoolers with ASDs, the fact that some early language competencies form part of the formal diagnostic criteria of ASD and diagnostic algorithms on research diagnostic instruments, the uneven profile of language competency in children with ASDs, and the difference between performance on measures of formal language competency in the testing situation and everyday language use. The current paper will review these challenges and suggest some possible approaches to overcome them, including using more than one measure of language ability and adopting a pragmatic approach to group composition and statistical analysis.

Autistic Disorder↗
PubMed2004

Measuring developmental progress of children with autism spectrum disorder on school entry using parent report.

Increasing numbers of children with autism spectrum disorder (ASD) are diagnosed in the preschool years, and their educational progress must be monitored. Parent questionnaire data can augment psychometric assessments and individual planning at low cost. One hundred and twenty-five parents of UK children who entered dedicated autism primary schools and units in two consecutive calendar years were asked to complete three questionnaires. Fifty-seven parents repeated the questionnaire measures one year later. Encouraging developmental progress was observed on the Vineland Adaptive Behavior Scales-Screener. Symptom severity as measured by the Social Communication Questionnaire did not change over time. The pattern of change scores on the Autism Treatment Evaluation Checklist was mixed, and confounding disadvantages this questionnaire. The study demonstrated that it is possible to collect useful information on the progress of children with ASD using parents as informants. Such data would assist in judging claims regarding developmental progress within particular programmes.

Autistic Disorder↗
PubMed2004

Performance of children with autism spectrum disorder on advanced theory of mind tasks.

Although a number of advanced theory of mind tasks have been developed, there is sparse information on whether performance on different tasks is associated. The study examined the performance of 20 high-functioning 6- to 12-year-old children with autism spectrum disorder and 20 controls on three high-level theory of mind tasks: Strange Stories, Cartoons and the children's version of the Eyes task. The pattern of findings suggests that the three tasks may share differing, non-specific, information-processing requirements in addition to tapping any putative mentalizing ability. They may also indicate a degree of dissociation between social-cognitive and social-perceptual or affective components of the mentalizing system.

Autistic Disorder↗
PubMed2003

Why is joint attention a pivotal skill in autism?

Joint attention abilities play a crucial role in the development of autism. Impairments in joint attention are among the earliest signs of the disorder and joint attention skills relate to outcome, both in the 'natural course' of autism and through being targeted in early intervention programmes. In the current study, concurrent and longitudinal associations between joint attention and other social communication abilities measured in a sample of infants with autism and related pervasive developmental disorders at age 20 months, and language and symptom severity at age 42 months, were examined. Extending the findings from previous studies, joint attention ability was positively associated with language gains and (lower) social and communication symptoms, and imitation ability was also positively associated with later language. Some specificity in the association between different aspects of joint attention behaviours and outcome was found: declarative, triadic gaze switching predicted language and symptom severity but imperative, dyadic eye contact behaviours did not. Further, although joint attention was associated with later social and language symptoms it was unrelated to repetitive and stereotyped symptoms, suggesting the latter may have a separate developmental trajectory. Possible deficits in psychological and neurological processes that might underlie the impaired development of joint attention in autism are discussed.

Attention↗
PubMed2003

Findings from a multidisciplinary clinical case series of females with Rett syndrome.

Systematic data from a multidisciplinary clinical assessment of a large series of females with Rett syndrome (RS; n=87) is presented. Participants' ages ranged from 2 years 1 month to 44 years 10 months. Areas assessed included oromotor skills, feeding problems, growth, breathing abnormalities, mobility, postural abnormalities and joint deformities, epilepsy, hand use and stereotypies, self-care, and cognitive and communication skills. Many previously reported trends in the presentation of RS over time were confirmed, notably the increasingly poor growth and near pervasiveness of fixed joint deformities and scoliosis in adulthood. In contrast, there was a slight trend towards improved autonomic function in adulthood, whereas feeding difficulties increased into middle childhood and then reached a plateau. Improvements in mobility into adolescence were followed by a decline in those skills in adulthood. Levels of dependency were high, confirming findings from previous studies. Despite the presence of repetitive hand movements, a range of hand-use skills was seen in individuals of all ages. Cognitive and communication skills were limited, but there was little evidence of deterioration of these abilities with age. These findings confirm that RS is not a degenerative condition and indicate that intervention and support to maintain and increase motor skills, daily living skills, and cognitive and communicative functioning are appropriate targets for individuals with RS.

Activities of Daily Living↗