How well does early diagnosis of autism stand the test of time? Follow-up study of children assessed for autism at age 2 and development of an early diagnostic service

Inter-rater reliability and stability of diagnoses of autism spectrum disorder in children identified through screening at a very young age

To examine the inter-rater reliability and stability of autism spectrum disorder (ASD) diagnoses made at a very early age in children identified through a screening procedure around 14 months of age. In a prospective design, preschoolers were recruited from a screening study for ASD. The inter-rater reliability of the diagnosis of ASD was measured through an independent assessment of a randomly selected subsample of 38 patients by two other psychiatrists. The diagnoses at 23 months and 42 months of 131 patients, based on the clinical assessment and the diagnostic classifications of standardised instruments, were compared to evaluate stability of the diagnosis of ASD. Inter-rater reliability on a diagnosis of ASD versus non-ASD at 23 months was 87% with a weighted kappa of 0.74 (SE 0.11). The stability of the different diagnoses in the autism spectrum was 63% for autistic disorder, 54% for pervasive developmental disorder, not otherwise specified (PDD-NOS), and 91% for the whole category of ASD. Most diagnostic changes at 42 months were within the autism spectrum from autistic disorder to PDD-NOS and were mainly due to diminished symptom severity. Children who moved outside the ASD category at 42 months made significantly larger gains in cognitive and language skills than children with a stable ASD diagnosis. In conclusion, the inter-rater reliability and stability of the diagnoses of ASD established at 23 months in this population-based sample of very young children are good.

One-year change in repetitive behaviours in young children with communication disorders including autism

Repetitive behaviours are a relatively neglected area of study in autism. Previous research has concluded that repetitive behaviour is inversely related to ability and that it tends to increase over the preschool years. One-hundred and four children ages 24-48 months, with autism, autism spectrum disorder (ASD) or other disorders, were followed for 13 months. Twelve items from the Autism Diagnostic Interview (ADI-R) were analysed, as well as diagnostic algorithm scores. Ability was related to degree of repetitive behaviours, except for one cluster of relatively able children. ADI-R repetitive behaviour algorithm scores increased over time; however, when all 12 behaviours were considered, there was a general decrease in impact upon the child's and family's activities. Reasons for this decrease are discussed.

The modified checklist for autism in toddlers: a follow-up study investigating the early detection of autism spectrum disorders

Autism spectrum disorders (ASD) often go undetected in toddlers. The Modified Checklist for Autism in Toddlers (M-CHAT) was used to screen 3,793 children aged 16-30 months from low- and high-risk sources; screen positive cases were diagnostically evaluated. Rescreening was performed on 1,416 children aged 42-54 months. Time 1 Positive Predictive Value (PPV) was .36 for the initial screening and .74 for the screening plus follow-up telephone interview; values were similar for Time2 PPV. When separating referral sources, PPV was low for the low-risk sample but acceptable with the followup telephone interview. Children with ASD from the low-risk and high-risk samples were highly similar. Results indicate that the M-CHAT continues to be a promising instrument for the early detection of ASD.

Repetitive and stereotyped behaviors in children with autism spectrum disorders in the second year of life

This study examined repetitive and stereotyped behaviors (RSB) in children with autism spectrum disorders (ASD, n = 50), developmental delays without ASD (DD; n = 25) and typical development (TD, n = 50) between 18 and 24 months of age. Children with ASD demonstrated significantly higher frequency and longer duration of RSB with objects, body, and sensory behaviors during a systematic behavior sample than both the DD and TD groups. RSB with objects were related to concurrent measures of symbolic capacity and social competence in the second year and predicted developmental outcomes as well as severity of autism symptoms at 3 years in children with communication delays. RSB in the second year appear to be important for early identification and prediction of developmental outcomes.

Repetitive and stereotyped movements in children with autism spectrum disorders late in the second year of life

OBJECTIVES

The purpose of this study was to examine group differences and relationships with later developmental level and autism symptoms using a new clinical tool developed to measure repetitive and stereotyped movements (RSM) in young children.

METHOD

Videotaped behavior samples using the Communication and Symbolic Behavior Scales Developmental Profile (CSBS; Wetherby & Prizant, 2002) were coded for children with autism spectrum disorders (ASD; n = 50), developmental delays without ASD (DD; n = 25), and typical development (TD; n = 50) between 18 and 24 months of age.

RESULTS

Children with ASD demonstrated significantly higher rate and larger inventory of RSM with objects and body during a systematic behavior sample than both the DD and TD groups. Measures of RSM were related to concurrent measures of social communication and predicted developmental outcomes and autism symptoms in the fourth year for the ASD group. None of the correlations between RSM and autism symptoms remained significant when controlling for CSBS Symbolic level. RSM with objects predicted unique variance in the severity of autism symptoms in the fourth year beyond that predicted by social communication measures alone.

CONCLUSIONS

This study provides support for the diagnostic significance of RSM in children under 24 months of age and documents the utility of this RSM measurement tool as a companion to the CSBS.

Stability of the autism diagnostic interview-revised from pre-school to elementary school age in children with autism spectrum disorders

This study examined the stability of scores on the ADI-R from pre-school to elementary school age in children with autism spectrum disorders (ASD). Participants were 35 children who, at T1, all had a clinical diagnosis of ASD. On initial assessment (mean age 3.5 years; SD 0.6 years), all met ADI-R algorithm criteria for autism. ADI-R assessments were repeated at follow up (FU; mean age 10.5 years; SD 0.8 years). Changes in ADI-R total, domain and ADI-R algorithm item scores were assessed. Twenty-eight children continued to score above the ADI-R cut-off for autism at FU, although significant decreases in ADI-R domain and item scores were also found. In conclusion while classification of children according to ADI-R criteria generally remained stable between pre-school and elementary school age, many children demonstrated significant improvements in symptom severity.

Studying the emergence of autism spectrum disorders in high-risk infants: methodological and practical issues

Detecting early signs of autism is essential for timely diagnosis and initiation of effective interventions. Several research groups have initiated prospective studies of high-risk populations including infant siblings, to systematically collect data on early signs within a longitudinal design. Despite the potential advantages of prospective studies of young children at high-risk for autism, there are also significant methodological, ethical and practical challenges. This paper outlines several of these challenges, including those related to sampling (e.g., defining appropriate comparison groups), measurement and clinical implications (e.g., addressing the needs of infants suspected of having early signs). We suggest possible design and implementation strategies to address these various challenges, based on current research efforts in the field and previous studies involving high-risk populations.

Diagnostic stability in very young children with autism spectrum disorders

Autism Spectrum Disorders (ASD) diagnosis in very young children may be delayed due to doubts about validity. In this study, 77 children received a diagnostic and developmental evaluation between 16 and 35 months and also between 42 and 82 months. Diagnoses based on clinical judgment, Childhood Autism Rating Scale, and the Autism Diagnostic Observation Schedule were stable over time. Diagnoses made using the Autism Diagnostic Interview were slightly less stable. According to clinical judgment, 15 children (19%) moved off the autism spectrum by the second evaluation; none moved onto the spectrum. Results indicate diagnostic stability at acceptable levels for diagnoses made at age 2. Movement off the spectrum may reflect true improvement based on maturation, intervention, or over-diagnosis at age 2.

Diagnosing autism spectrum disorders in pre-school children using two standardised assessment instruments: the ADI-R and the ADOS

The reliable diagnosis of Autism/Autism Spectrum Disorder in pre-school children is important for access to early intervention and for accurate ascertainment for research. This paper explores the combined use of two standardised assessment instruments--the Autism Diagnostic Interview Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS)--in a large sample of pre-school children. The children were recruited to research studies, and a 'best estimate' clinical diagnosis reached. The findings show good agreement between the instruments especially for children with core Autism. The instruments appear to have a complementary effect in aiding diagnosis and confirm the importance of a multidisciplinary assessment process with access to information from different sources and settings. The presence of repetitive behaviours during the ADOS appeared of diagnostic significance.

Predictors of optimal outcome in toddlers diagnosed with autism spectrum disorders

A diagnosis of autism spectrum disorder (ASD) is usually taken to be permanent. In this study, 13 two-year-old children with ASD lost the diagnosis by age 4, at which time they scored within the normal range on standardized measures of cognitive and adaptive functioning. No differences were found in symptom severity, socialization, or communication between children who lost the ASD diagnosis and children who did not, but children with PDD-NOS were significantly more likely than those with full autistic disorder to move off the spectrum. The clearest distinguishing factor was motor skills at age 2. Results support the idea that some toddlers with ASD can lose their diagnosis and suggest that this is difficult to predict.

Predictors of optimal outcome in toddlers diagnosed with autism spectrum disorders

A diagnosis of autism spectrum disorder (ASD) is usually taken to be permanent. In this study, 13 two-year-old children with ASD lost the diagnosis by age 4, at which time they scored within the normal range on standardized measures of cognitive and adaptive functioning. No differences were found in symptom severity, socialization, or communication between children who lost the ASD diagnosis and children who did not, but children with PDD-NOS were significantly more likely than those with full autistic disorder to move off the spectrum. The clearest distinguishing factor was motor skills at age 2. Results support the idea that some toddlers with ASD can lose their diagnosis and suggest that this is difficult to predict.

Restricted and repetitive behaviors in young children with autism spectrum disorders

Restricted and repetitive behaviors (RRBs) on the Autism Diagnostic Interview- Revised (ADI-R: Lord, Rutter, & Le Couteur (1994) were examined in 165 children with Autism Spectrum Disorders (ASD), 49 children with non-spectrum developmental disorders (DD), and 65 children with typical development (TD) at approximately 2 years of age. A factor analysis found evidence for a repetitive sensorimotor (RSM) factor and an insistence on sameness (IS) factor. Behaviors that loaded on the RSM factor were prevalent in children with ASD and significantly more common and severe than in children with DD or TD. On average, children with ASD had more RSM behaviors. Behaviors that loaded on the IS factor were relatively uncommon and did not differ in prevalence or severity across groups.

Follow-up of children diagnosed with pervasive developmental disorders: stability and change during the preschool years

Forty-one children with pervasive developmental disorders (PDDs) receiving eclectic services were assessed twice during their preschool years. Measures were compared over time for the whole group and for diagnostic subgroups: Childhood autism (CA group) and Other PDDs group. The mean intelligence quotient/developmental quotient (IQ/DQ) of the whole group was stable (P = 0.209) and scores on the Childhood Autism Rating Scale (CARS) decreased (P = 0.001). At time 2, the CA group was more impaired than the other PDDs group: autistic symptoms were more severe (P = 0.01), adaptive behavior scores were lower (P = 0.014), and a trend for lower IQ/DQs (P = 0.06). Children in this study seemed to fare better than reported in previous follow-up studies on children with autism.

Can a diagnosis of Asperger syndrome be made in very young children with suspected autism spectrum disorder?

Of a cohort of 104 children with Autism, PDD-NOS or specific language disorder, recruited at age 2-3 years of age, only three appeared to meet diagnostic assessment criteria for Asperger syndrome (AS). The children were followed up at 4-5 years, and assessments at both time points included the Autism Diagnostic Interview (ADI-R), the Autism Diagnostic Observation Schedule (ADOS) and the Mullen Scales of Early Learning. The paper explores the reasons why so few children with possible AS were identified early, including problems inherent in the assessment tools and the range of normal variation within characteristics required for a diagnosis. Only 10 children altogether had first words by 24 months, and abilities in the average range, and 9 were followed up. All of these able children had varied repetitive behaviours, and these increased in terms of ADI-R algorithm score over a 13 month interval. However, items concerning resistance to change and liking of routines tended to decrease in terms of reported impact on the child and family. Repetitive behaviours seem significant in the early referral of able children for a PDD diagnosis, but identification of children with AS is more likely to occur reliably once children are older and enter school.