Cheryl Dissanayake

Autism Spectrum Disorders in infancy and toddlerhood : a review of the evidence on early signs, early identification tools, and early diagnosis.

To date, the biological basis of autism spectrum disorders (ASDs) remains unknown. Thus, identification and diagnosis are reliant on behavioral presentation and developmental history. There have been significant advances in our knowledge of the early signs of ASD through the use of retrospective videotape analysis, parental report, screening studies, and more recently, studies on high-risk infant siblings. Despite behavioral markers being identified within the first year of life, the current average age of diagnosis for ASD remains at approximately 3 years or older. Consequently, these children are not receiving intervention in their early years, which is increasingly recognized as an important time to begin intervention. There remains little research on the prospective identification of these children in a community-based sample before 18 months. It is recommended that future prospective studies monitor behavior repeatedly over time, thereby increasing the opportunity to identify early manifestations of ASD and facilitating the charting of subtle behavioral changes that occur in the development of infants and toddlers with ASD.

Molecular and cognitive predictors of the continuum of autistic behaviours in fragile X

The distributions of scores for autistic behaviours obtained from the Autism Diagnostic Observation Scale-Generic (ADOS-G) were investigated in 147 males and females affected with the full mutation in the fragile X mental retardation 1 (FMR1) gene, in 59 individuals with the premutation, and in 42 non-fragile X relatives, aged 4-70 years. The scores representing communication and social interaction were continuously distributed across the two fragile X groups, and they were significantly elevated compared with the non-fragile X controls. Strong relationships were found between both these scores and FMRP deficits, but they became insignificant for social interaction, and the sum of social interaction and communication scores, when FSIQ was included as another predictor of autism scores. Other significant predictors of these scores in both sexes were those executive skills which related to verbal fluency, and to the regulation and control of motor behaviour. Overall, our data have shown that cognitive impairment, especially of verbal skills, best explains the comorbidity of autism and fragile X. This implies some more fundamental perturbations of specific neural connections which are essential for both specific behaviours and cognition. We also emphasize that FXS offers a unique molecular model for autism since FMRP regulates the translation of many other genes involved in synaptic formation and plasticity which should be natural targets for further exploration.

Parenting stress and autism: The role of age, autism severity, quality of life and problem behaviour of children and adolescents with autism

While stress is a common experience for parents caring for a child with a developmental disability, current measures fail to distinguish between general stress in parents and the demands of parenting and perceptions of parenting skills (parenting stress). This study examined differences in ‘parenting stress’ reported by parents of children with autism and typically developing children. This study examined the role of child characteristics (age, autism severity, child quality of life and problem behaviour) on parenting stress in 150 parents of cognitively able children and adolescents with autism. The results revealed that child hyperactivity was the only factor significantly related to parenting stress in parents of children with autism, overruling measures of autism severity and child quality of life. This finding indicates the significant influence of problematic behaviours on parenting demands and perceptions of parenting skills in parents of children with autism, over other child characteristics conceived as within the parent’s control. Study implications for future research are discussed.

Are emotion impairments unique to, universal, or specific in autism spectrum disorder? A comprehensive review

There is widespread belief that individuals with Autism Spectrum Disorders (ASDs) are “emotionally detached” from others. This comprehensive review examines the empirical evidence for this assumption, addressing three critical questions: (1) Are emotion-processing impairments universal in ASD? (2) Are they specific, or can they be explained by deficits in other domains? (3) Is the emotion processing profile seen in ASD unique to these conditions? Upon review of the literature (over 200 studies), we conclude that: (1) emotion-processing impairments might not be universal in ASD, as suggested by variability across participants and across emotion-processing tasks; (2) emotion-processing impairments might not be specific to ASD, as domain-general processes appear to account for some of these impairments; and (3) the specific pattern of emotion-processing strengths and weaknesses observed in ASD, involving difficulties with processing social versus non-social, and complex versus simple emotional information (with impairments more consistently reported on implicit than explicit emotion-processing tasks), appears to be unique to ASD. The emotion-processing profile observed in ASD might be best understood as resulting from heterogeneous vulnerabilities in different components of an “emotional communication system” that, in typical development, emerges from the interplay between domain-general cognitive, social and affective processes.

Growth in stature and head circumference in high-functioning autism and Asperger disorder during the first 3 years of life

Little effort has been made to characterize the developmental anatomic phenotype of autism; although there is evidence of an increased head circumference and brain size, few other physical characteristics have been studied. The head circumference, body length/height, and weight measurements of infants, who were later diagnosed with high-functioning autism (HFA, n = 16) and Asperger disorder (AsD, n = 12), were extracted from health records over the first 3 years of life and compared to the measurements of a matched normal control group (n = 19). Using linear mixed-effects models, no differences were found in the average growth rate for head circumference, stature, or weight between the children with HFA and AsD. However, a significantly higher growth rate in body length/height and weight was found for the combined group of children with HFA and AsD compared to the normal control group. A trend toward higher growth rate in head circumference was also found among the former group. The results indicate that growth dysregulation in autism is not specific to the brain but also involves growth in stature.

Prospective identification of autism spectrum disorders in infancy and toddlerhood using developmental surveillance: the social attention and communication study.

Objective: Despite behavioral markers of autism spectrum disorders (ASDs) being evident within the first year of life, there remains little research on the prospective identification of these children in a community-based setting before 18 months. The aim in the Social Attention and Communication Study was to identify infants and toddlers at risk of an ASD during their first 2 years. Methods: A total of 241 Maternal and Child Health nurses were trained on the early signs of ASDs at 8, 12, 18 and 24 months. Using a developmental surveillance approach with a community-based sample, a cohort of 20,770 children was monitored on early social attention and communication behaviors. Those infants/toddlers identified as “at risk” were referred to the Social Attention and Communication Study team from 12 months for developmental and diagnostic assessments at 6 monthly intervals, until 24 months. Results: A total of 216 children were referred, with 110 being further assessed. Of these, 89 children were classified with an ASD at 24 months, and 20 children had developmental and/or language delays, resulting in a Positive Predictive value of 81%. The estimated rate of ASDs in the Social Attention and Communication Study cohort ranged from 1:119 to 1:233 children. Estimated sensitivity ranged from 69% to 83.8%, and estimated specificity ranged from 99.8% to 99.9%. Conclusion: Developmental surveillance of social and communication behaviors, which differ according to the age at which the child is monitored, enables the accurate identification of children at risk for ASDs between 12 and 24 months. Education on the early signs is recommended for all primary health care professionals to facilitate early identification of ASDs.

A comparative study of the spontaneous social interactions of children with high-functioning autism and children with Asperger's disorder

A comparative observational study was undertaken of the spontaneous social interactions of children with high-functioning autism and Aspergers disorder. The sample comprised 20 children with high-functioning autism, 19 children with Aspergers disorder and 17 typically developing children matched on chronological age and overall mental age. A one–zero time sampling technique was used in live coding of the childrens spontaneous social and play behaviours in the schoolyard. Few differences were found between children with high-functioning autism and Aspergers disorder on the dimensions of social interaction investigated. In contrast, the social behaviour of both clinical samples often deviated markedly from that of the typically developing children. The findings confirmed that although children with high-functioning autism or Aspergers disorder are often socially isolated relative to their typically developing peers, they are capable of spontaneously engaging socially with other children. The results were supportive of the hypothesis that Aspergers disorder is on a continuum with autistic disorder.

An investigation of pretend play, mental state terms and false belief understanding: In search of a metarepresentational link

The aim of this study was to investigate the association between false belief comprehension, the exhibition of pretend play and the use of mental state terms in pre-school children. Forty children, aged between 36 and 54 months were videotaped engaging in free play with each parent. The exhibition of six distinct acts of pretend play and the expression of 16 mental state terms were coded during play. Each child was also administered a pantomime task and three standard false belief tasks. Reliable associations were also found between false belief performance and the pretence categories of object substitution and role assignment, and the exhibition of imaginary object pantomimes. Moreover, the use of mental state terms was positively correlated with false belief and the pretence categories of object substitution, imaginary play and role assignment, and negatively correlated with the exhibition of body part object pantomimes. These findings indicate that the development of a mental state lexicon and some, but not all, components of pretend play are dependent on the capacity for metarepresentational cognition.

Early markers of autism spectrum disorders in infants and toddlers prospectively identified in the Social Attention and Communication Study

The Social Attention and Communication Study involved the successful implementation of developmental surveillance of the early markers of autism spectrum disorders in a community-based setting. The objective in the current study was to determine the most discriminating and predictive markers of autism spectrum disorders used in the Social Attention and Communication Study at 12, 18 and 24 months of age, so that these could be used to identify children with autism spectrum disorders with greater accuracy. The percentage of ‘yes/no’ responses for each behavioural marker was compared between children with autistic disorder (n = 39), autism spectrum disorder (n = 50) and developmental and/or language delay (n = 20) from 12 to 24 months, with a logistic regression also conducted at 24 months. Across all ages, the recurring key markers of both autistic disorder and autism spectrum disorder were deficits in eye contact and pointing, and from 18 months, deficits in showing became an important marker. In combination, these behaviours, along with pretend play, were found to be the best group of predictors for a best estimate diagnostic classification of autistic disorder/autism spectrum disorder at 24 months. It is argued that the identified markers should be monitored repeatedly during the second year of life by community health-care professionals.

Autistic children's responses to separation and reunion with their mothers.

Observed 16 autistic, 16 normal, and 16 Down syndrome children (ages 3–6 years during separation and reunion with their mother in a laboratory playroom over three sessions. Childrens responses to separation and reunion were assigned to one of five behavioral patterns that were weighted for intensity or level of response. No differences were found between groups in their behavioral responses during separation or reunion. Moreover, children in each group altered their responses according to the environmental setting which was varied over the three sessions. However, the autistic and Down syndrome groups did differ from the normal group in their consistency of behavioral patterns over the three observation sessions; both the former groups showed more individual variation in their separation and reunion patterns indicating that the expression of these patterns may be influenced by their associated developmental delay.