Autism spectrum disorder in the second year: stability and change in syndrome expression

OBJECTIVES: Increasing numbers of young children referred for a differential diagnosis of autism spectrum disorders (ASD) necessitates better understanding of the early syndrome expression and the utility of the existing state-of-the art diagnostic methods in this population. METHOD: Out of 31 infants under the age of 2 years referred for a differential diagnosis, 19 were diagnosed with autism, and 9 with pervasive developmental disorder - not otherwise specified (PDD-NOS) when reassessed at 3 years. We examined 1) the symptoms of ASD in the second year and changes in the syndrome expression by the age of three; 2) relationship between expert-assigned clinical diagnosis and diagnostic classification based on Autism Diagnostic Observation Schedule-Generic (ADOS-G) and Autism Diagnostic Interview-Revised (ADI-R) in the second year; 3) the relationship between direct observation and parental report of ASD symptoms. RESULTS: Symptoms of autism and PDD-NOS in the second year were pronounced and stability of the clinical diagnosis was high. The agreement between clinician-assigned autism but not PDD-NOS diagnosis and the ADOS-G was high. However, sensitivity of the ADI-R diagnostic classification of autism was poor. Comparison of concurrent parental report and direct observation revealed discrepancies in severity ratings of key dyadic social behaviors. Changes in communication reflected acquisition of language accompanied by the emergence of unusual language characteristics. Symptoms of social dysfunction were relatively stable over time, and so was the severity of stereotyped behaviors. CONCLUSIONS: The study provides support for stability of clinical diagnosis and syndrome expression in the second year and highlights advantages and limitations of the ADI-R and ADOS-G for diagnosing and documenting symptoms of ASD in infants.     

Early diagnosis of autism spectrum disorder: stability and change in clinical diagnosis and symptom presentation

Background: Although a diagnosis of autism spectrum disorder (ASD) appears to be stable in children as young as age three, few studies have explored stability of a diagnosis in younger children. Predictive value of diagnostic tools for toddlers and patterns of symptom change are important considerations for clinicians making early diagnoses. Most findings come from high‐risk samples, but reports on children screened in community settings are also needed. Methods: Stability of diagnosis and Autism Diagnostic Observation Schedule – Toddler Module (ADOS‐T) classifications and scores was examined across two time points in a sample of 82 children identified through the FIRST WORDS^® Project. Children received two comprehensive diagnostic evaluations at average ages of 19.39 (SD = 2.12) and 36.89 (SD = 3.85) months. Results: Stability was 100% when confirming and ruling out a diagnosis of ASD based on a comprehensive diagnostic evaluation that included clinic and home observations, although diagnosis was initially deferred for 17% of the sample. Receiver Operating Characteristic curves revealed excellent sensitivity and acceptable specificity for the ADOS‐T compared to concurrent diagnosis. Logistic regressions indicated good predictive value of initial ADOS‐T scores for follow‐up diagnosis. Finally, both ASD and Non‐ASD children demonstrated a decrease in Social Affect scores (i.e., improvement), whereas children with ASD demonstrated an increase in Restricted and Repetitive Behavior scores (i.e., worsening), changes that were accounted for by nonverbal developmental level in mixed model analyses. Conclusions: Short‐term stability was documented for children diagnosed at 19 months on average, although a minority of children initially showed unclear diagnostic presentations. Findings highlight utility of the ADOS‐T in making early diagnoses and predicting follow‐up diagnoses. Children with ASD demonstrated improvement in social communication behaviors and unfolding of repetitive behaviors, suggesting that certain early patterns of change in symptoms may be characteristic of ASD.     

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.     

Similar developmental trajectories in autism and Asperger syndrome: from early childhood to adolescence

Objective:  The objective of this study was to chart the developmental trajectories of high-functioning children with autism spectrum disorders (ASD) from early childhood to adolescence using the presence and absence of structural language impairment (StrLI) as a way of differentiating autism from Asperger syndrome (AS).
Method:  Sixty-four high-functioning children with ASD were ascertained at 4–6 years of age from several different regional diagnostic and treatment centers. At 6–8 years of age, the ADI-R and the Test of Oral Language Development were used to define an autism group (those with StrLI at 6–8 years of age) and an AS group (those without StrLI). Growth curve analysis was then used to chart the developmental trajectories of these children on measures of autistic symptoms, and adaptive skills in communication, daily living and socialization.
Results:  Differentiating the ASD group in terms of the presence/absence of StrLI provided a better explanation of the variation in growth curves than not differentiating high-functioning ASD children. The two groups had similar developmental trajectories but the group without StrLI (the AS group) was functioning better and had fewer autistic symptoms than the group with StrLI (the autism group) on all measures across time. The differences in outcome could not be explained by non-verbal IQ or change in early language skills.
Conclusion:  Distinguishing between autism and Asperger syndrome based on the presence or absence of StrLI appears to be a clinically useful way of classifying ASD sub-types.     

Diagnostic labelling of autism spectrum disorders in NSW

Aim:   To describe the use of diagnostic labels by clinicians for children with autism spectrum disorders (ASD) and calculate the label-specific and overall agreement between diagnostic labels and Diagnostic and Statistical Manual of Mental Disorders – Fourth Edition (DSM-IV) diagnoses provided by the same clinician.
Methods:   State-wide active surveillance was used to ascertain children newly recognised with one or more DSM-IV criteria for autistic disorder aged 0–15 years (incident cases) in New South Wales (NSW) between July 1999 and December 2000. Clinicians were asked to supply a diagnostic label and then complete DSM-IV criteria for each child reported.
Results:   Questionnaires with diagnostic label and DSM-IV criteria were returned for 348 children. The agreement between labels used and diagnosis based on DSM-IV classification system was the highest for autism (97%) and lower for labels of Asperger disorder, pervasive developmental disorder – not otherwise specified or atypical autism (27%). Kappa overall agreement was 0.31. Level of agreement between label and DSM-IV diagnosis was similar for questionnaires completed by multidisciplinary teams, psychiatrists, paediatricians and psychologists working as part of a team.
Conclusion:   A lack of agreement between the diagnostic labelling used by clinicians and diagnosis based on DSM-IV criteria indicates a lack of consistency in diagnostic communication that is necessary to provide best clinical care, appropriate services and relevant information to parents and carers.     

Using self-report to identify the broad phenotype in parents of children with autistic spectrum disorders: a study using the Autism-Spectrum Quotient

Background:  The concept of the 'broad phenotype' of autism refers to the finding that relatives of people with autism often have mild forms of autistic-like characteristics, such as social and communicative difficulties. This study used the Autism Spectrum Quotient (AQ), a questionnaire devised to assess features of the broad phenotype in adults, with parents of people with autism, to see whether they would be more likely to obtain extreme scores than a control group.
Methods:  The AQ was administered to parents of 69 people with an autism spectrum disorder and parents of 52 controls.
Results:  On two of the five subscales of the AQ, social skills and communication, parents of people with autism obtained higher scores than control parents. The other three scales, attention to detail, attention switching, and imagination, did not differentiate groups. The correlation between social skills and communication scales was .663. The scales can be combined to give an index of broad phenotype.
Conclusions:  The AQ appears to be sensitive to the broad phenotype, provided attention is restricted to the social skills and communication scales.     

Cognitive behavioral therapy for anxiety in children with autism spectrum disorders: a randomized, controlled trial

Background:  Children with autism spectrum disorders often present with comorbid anxiety disorders that cause significant functional impairment. This study tested a modular cognitive behavioral therapy (CBT) program for children with this profile. A standard CBT program was augmented with multiple treatment components designed to accommodate or remediate the social and adaptive skill deficits of children with ASD that could pose barriers to anxiety reduction.
Method:  Forty children (7–11 years old) were randomly assigned to 16 sessions of CBT or a 3-month waitlist (36 completed treatment or waitlist). Therapists worked with individual families. The CBT model emphasized behavioral experimentation, parent-training, and school consultation. Independent evaluators blind to treatment condition conducted structured diagnostic interviews and parents and children completed anxiety symptom checklists at baseline and posttreatment/postwaitlist.
Results:  In intent-to-treat analyses, 78.5% of the CBT group met Clinical Global Impressions-Improvement scale criteria for positive treatment response at posttreatment, as compared to only 8.7% of the waitlist group. CBT also outperformed the waitlist on diagnostic outcomes and parent reports of child anxiety, but not children's self-reports. Treatment gains were maintained at 3-month follow-up.
Conclusions:  The CBT manual employed in this study is one of the first adaptations of an evidence-based treatment for children with autism spectrum disorders. Remission of anxiety disorders appears to be an achievable goal among high-functioning children with autism.     

Eye-movement patterns are associated with communicative competence in autistic spectrum disorders

Background:  Investigations using eye-tracking have reported reduced fixations to salient social cues such as eyes when participants with autism spectrum disorders (ASD) view social scenes. However, these studies have not distinguished different cognitive phenotypes.
Methods:  The eye-movements of 28 teenagers with ASD and 18 typically developing peers were recorded as they watched videos of peers interacting in familiar situations. Within ASD, we contrasted the viewing patterns of those with and without language impairments. The proportion of time spent viewing eyes, mouths and other scene details was calculated, as was latency of first fixation to eyes. Finally, the association between viewing patterns and social-communicative competence was measured.
Results:  Individuals with ASD and age-appropriate language abilities spent significantly less time viewing eyes and were slower to fixate the eyes than typically developing peers. In contrast, there were no differences in viewing patterns between those with language impairments and typically developing peers. Eye-movement patterns were not associated with social outcomes for either language phenotype. However, increased fixations to the mouth were associated with greater communicative competence across the autistic spectrum.
Conclusions:  Attention to both eyes and mouths is important for language development and communicative competence. Differences in fixation time to eyes may not be sufficient to disrupt social competence in daily interactions. A multiple cognitive deficit model of ASD, incorporating different language phenotypes, is advocated.     

Sensory clusters of toddlers with autism spectrum disorders: differences in affective symptoms

Background:  Individuals with autism spectrum disorders (ASDs) show variability in their sensory behaviors. In this study we identified clusters of toddlers with ASDs who shared sensory profiles and examined differences in affective symptoms across these clusters.
Method:  Using cluster analysis 170 toddlers with ASDs were grouped based on parent rating of the Infant Toddler Sensory Profile ( Dunn, 2002 ) under-responsivity, over-responsivity, and seeking scales. Affective symptoms were evaluated with the Infant Toddler Social Emotional Assessment ( Carter & Briggs-Gowan, 2005 ).
Results:  Three clusters were identified: (1) low frequency of sensory symptoms ( n  =   44); (2) high frequency of symptoms ( n  =   49); and (3) mixed ( n  =   77); high frequency of under-and over-responsivity and low frequency of seeking). Relative to the low frequency cluster, parents rated toddlers in the high frequency and mixed clusters (both characterized by high frequencies of sensory under- and over-responsivity) as higher on negative emotionality, depression, and anxiety symptoms. Sensory and affective differences among clusters remained after co-varying severity of ASD symptoms.
Conclusions:  Interdisciplinary assessments are recommended for toddlers with ASDs in order to identify the interplay of sensory and affective symptoms.     

Infant and toddler oral- and manual-motor skills predict later speech fluency in autism

Background:  Spoken and gestural communication proficiency varies greatly among autistic individuals. Three studies examined the role of oral- and manual-motor skill in predicting autistic children's speech development.
Methods:  Study 1 investigated whether infant and toddler oral- and manual-motor skills predict middle childhood and teenage speech fluency; Study 2 verified those early infant and toddler predictions with historical home video; and Study 3 assessed the relation between autistic children's current-day oral-motor skill and their speech fluency.
Results:  Infant and toddler oral-motor and manual-motor skills inter-correlated significantly, distinguished autistic children ( N  = 115) from typically developing children ( N  = 44), and distinguished autistic children whose current-day speech was minimally fluent ( N  = 33), moderately fluent ( N  = 39), and highly fluent ( N  = 39). These results were corroborated by analysis of historical home video ( N  = 32) and verified with current-day assessment ( N  = 40).
Conclusions:  The prominent associations among early oral- and manual-motor skills and later speech fluency bear implications for understanding communication in autism. For instance, these associations challenge the common assumption (made even in diagnostic criteria) that manual modes of communication are available to autistic individuals – if simply they choose to use them. These associations also highlight a potential confound from manual-motor skills when assessing autistic cognition, receptive language, and 'nonverbal' social communication.     

Latent class analysis of early developmental trajectory in baby siblings of children with autism

Background: Siblings of children with autism (sibs‐A) are at increased genetic risk for autism spectrum disorders (ASD) and milder impairments. To elucidate diversity and contour of early developmental trajectories exhibited by sibs‐A, regardless of diagnostic classification, latent class modeling was used. Methods: Sibs‐A (N = 204) were assessed with the Mullen Scales of Early Learning from age 6 to 36 months. Mullen T scores served as dependent variables. Outcome classifications at age 36 months included: ASD (N = 52); non‐ASD social/communication delay (broader autism phenotype; BAP; N = 31); and unaffected (N = 121). Child‐specific patterns of performance were studied using latent class growth analysis. Latent class membership was then related to diagnostic outcome through estimation of within‐class proportions of children assigned to each diagnostic classification. Results: A 4‐class model was favored. Class 1 represented accelerated development and consisted of 25.7% of the sample, primarily unaffected children. Class 2 (40.0% of the sample), was characterized by normative development with above‐average nonverbal cognitive outcome. Class 3 (22.3% of the sample) was characterized by receptive language, and gross and fine motor delay. Class 4 (12.0% of the sample), was characterized by widespread delayed skill acquisition, reflected by declining trajectories. Children with an outcome diagnosis of ASD were spread across Classes 2, 3, and 4. Conclusions: Results support a category of ASD that involves slowing in early non‐social development. Receptive language and motor development is vulnerable to early delay in sibs‐A with and without ASD outcomes. Non‐ASD sibs‐A are largely distributed across classes depicting average or accelerated development. Developmental trajectories of motor, language, and cognition appear independent of communication and social delays in non‐ASD sibs‐A.     

White matter fractional anisotrophy differences and correlates of diagnostic symptoms in autism

Background:  Individuals with autism have impairments in 3 domains: communication, social interaction and repetitive behaviours. Our previous work suggested early structural and connectivity abnormalities in prefrontal-striato-temporal-cerebellar networks but it is not clear how these are linked to diagnostic indices.
Method:  Children with autism (IQ > 70) aged 6 to 14 years old and matched typically developing controls were studied using diffusion tensor imaging. Voxel-based methods were used to compare fractional anisotrophy (FA) measures in each group and to correlate FA measures in the autism group with the diagnostic phenotype described by the Autism Diagnostic Interview – Revised (ADI-R) algorithm for ICD-10.
Results:  After controlling for the effects of age and white matter volume, we found that FA in the autism group was significantly lower than controls in bilateral prefrontal and temporal regions, especially in the right ventral temporal lobe adjacent to the fusiform gyrus. FA was greater in autism in the right inferior frontal gyrus and left occipital lobe. We observed a tight correlation between lower FA and higher ADI-R diagnostic algorithm scores across white matter tracts extending from these focal regions of group difference. Communication and social reciprocity impairments correlated with lower FA throughout fronto-striato-temporal pathways. Repetitive behaviours correlated with white matter indices in more posterior brain pathways, including splenium of the corpus callosum and cerebellum.
Conclusions:  Our data support the position that diagnostic symptoms of autism are associated with a core disruption of white matter development.     

What's in a game: the effect of social motivation on interference control in boys with ADHD and autism spectrum disorders

Background:  Children with attention deficit hyperactivity disorder (ADHD) and with autism spectrum disorders (ASD) are known to have cognitive control deficits. Some studies suggest that such deficits may be reduced when motivation is increased through tangible reinforcers. Whether these deficits can also be modulated by non-tangible reinforcers has hardly been studied.
Methods:  Therefore, the effect of social motivation on the ability to suppress irrelevant information (i.e., interference control) was investigated in 22 ADHD boys, 22 ASD boys, and 33 typically developing (TD) boys. An adapted Eriksen Flanker task was administered under a motivational condition in which the boys were told that they were competing with peers, and under a neutral condition in which standard instructions were given.
Results:  In comparison with TD boys, boys with ADHD were impaired even when no interference was present, while this was not the case for the ASD boys. All groups benefited from the motivation manipulation, i.e., their performance increased when they thought they were competing with peers. Although the boys with ADHD were still slower than TD boys when motivated, they performed as accurately as TD boys. Children with ASD also improved slightly in accuracy and response speed, but this did not reach significance.
Conclusion:  Children with ADHD are able to exert sufficient cognitive control when they are motivated, which is in line with the current models of ADHD. However, motivation seems to have a general effect on performance and is not solely related to cognitive control abilities. In contrast, this effect was not obtained in children with ASD.     

Relationship between special abilities and autistic-like traits in a large population-based sample of 8-year-olds

Background:  The raised incidence of special abilities or 'savant skills' among individuals with autism spectrum disorders (ASD) relative to other developmental disorders suggests an association between the traits characteristic of ASD and special abilities. The purpose of this study was to investigate the association between special abilities and ASD-like traits.
Methods:  This study compared the scores of 6,426 8-year-olds with and without parent-reported special abilities on a screening questionnaire for ASD-like traits in three areas: social interaction, communication, and restricted and repetitive behaviours and interests. Measures of IQ, sex, and socioeconomic status (SES) were also compared.
Results:  From parent report, children with special abilities showed significantly more ASD-like traits than those without such abilities. General intelligence did not mediate this relationship: IQ was found to be positively associated with ability, but negatively associated with ASD-like traits. Special abilities were more strongly associated with restricted/repetitive characteristics than with social or communication traits.
Conclusions:  Results support the association between special abilities and ASD-like traits, and expand it to traits in the general population. The type of nonsocial traits most strongly associated with parental reports of special abilities suggests a link to a featural information processing style, or 'weak central coherence'.     

Reduced change blindness suggests enhanced attention to detail in individuals with autism

Background:  The phenomenon of change blindness illustrates that a limited number of items within the visual scene are attended to at any one time. It has been suggested that individuals with autism focus attention on less contextually relevant aspects of the visual scene, show superior perceptual discrimination and notice details which are often ignored by typical observers.
Methods:  In this study we investigated change blindness in autism by asking participants to detect continuity errors deliberately introduced into a short film. Whether the continuity errors involved central/marginal or social/non-social aspects of the visual scene was varied. Thirty adolescent participants, 15 with autistic spectrum disorder (ASD) and 15 typically developing (TD) controls participated.
Results:  The participants with ASD detected significantly more errors than the TD participants. Both groups identified more errors involving central rather than marginal aspects of the scene, although this effect was larger in the TD participants. There was no difference in the number of social or non-social errors detected by either group of participants.
Conclusion:  In line with previous data suggesting an abnormally broad attentional spotlight and enhanced perceptual function in individuals with ASD, the results of this study suggest enhanced awareness of the visual scene in ASD. The results of this study could reflect superior top-down control of visual search in autism, enhanced perceptual function, or inefficient filtering of visual information in ASD.     

The structure of the Autism Diagnostic Interview-Revised: diagnostic and phenotypic implications

Background:  Multivariate statistics can assist in refining the nosology and diagnosis of pervasive developmental disorders (PDD) and also contribute important information for genetic studies. The Autism Diagnostic Interview-Revised (ADI-R) is one of the most widely used assessment instruments in the field of PDD. The current study investigated its factor structure and convergence with measures of adaptive, language, and intellectual functioning.
Methods:  Analyses were conducted on 1,861 individuals with PDD between the ages of 4 and 18 years (mean = 8.3, SD = 3.2). ADI-R scores were submitted to confirmatory factor analysis (CFA) and exploratory factor analysis (EFA). Analyses were conducted according to verbal status ( n  =   1,329 verbal, n  =   532 nonverbal) and separately for algorithm items only and for all items. ADI-R scores were correlated with scores on measures of adaptive, language, and intellectual functioning.
Results:  Several factor solutions were examined and compared. CFAs suggested that two- and three-factor solutions were similar, and slightly superior to a one-factor solution. EFAs and measures of internal consistency provided some support for a two-factor solution consisting of social and communication behaviors and restricted and repetitive behaviors. Measures of functioning were not associated with ADI-R domain scores in nonverbal children, but negatively correlated in verbal children.
Conclusions:  Overall, data suggested that autism symptomatology can be explained statistically with a two-domain model. It also pointed to different symptoms susceptible to be helpful in linkage analyses. Implications of a two-factor model are discussed.     

Factors that influence vocabulary development in two-year-old children

Background:  This research explored the relative impact of demographic, cognitive, behavioural, and psycholinguistic factors on vocabulary development in two-year-old children.
Methods:  Two hundred and thirty-two children (24–30 months) were tested on expressive and receptive vocabulary, cognitive development, word learning and working memory skills. Parents completed a British adaptation ( Klee & Harrison, 2001 ) of the MacArthur–Bates Communicative Development Inventory (CDI; Fenson et al., 1993 ), a demographic questionnaire and a questionnaire regarding the child's social-emotional behaviour.
Results:  Several demographic, child and processing variables were significantly correlated with CDI (vocabulary) scores, but the only significant unique predictors of CDI scores were nonword repetition (NWR; R ² change = .36), sex ( R ² change = .05) and age ( R ² change = .04). Scores were only included when a child completed the entire NWR test (77% of toddlers).
Conclusions:  The NWR task used in this experiment maximised participation in this group of toddlers, and was a strong predictor of vocabulary ability. Longitudinal research is warranted to explore the independent and reciprocal growth in working memory and language skills in children.     

Intervention targeting development of socially synchronous engagement in toddlers with autism spectrum disorder: a randomized controlled trial

Background: Social and communication impairments are core deficits and prognostic indicators of autism. We evaluated the impact of supplementing a comprehensive intervention with a curriculum targeting socially synchronous behavior on social outcomes of toddlers with autism spectrum disorders (ASD). Methods: Fifty toddlers with ASD, ages 21 to 33 months, were randomized to one of two six‐month interventions: Interpersonal Synchrony or Non‐Interpersonal Synchrony. The interventions provided identical intensity (10 hours per week in classroom), student‐to‐teacher ratio, schedule, home‐based parent training (1.5 hours per month), parent education (38 hours), and instructional strategies, except the Interpersonal Synchrony condition provided a supplementary curriculum targeting socially engaged imitation, joint attention, and affect sharing; measures of these were primary outcomes. Assessments were conducted pre‐intervention, immediately post‐intervention, and, to assess maintenance, at six‐month follow‐up. Random effects models were used to examine differences between groups over time. Secondary analyses examined gains in expressive language and nonverbal cognition, and time effects during the intervention and follow‐up periods. Results: A significant treatment effect was found for socially engaged imitation (p = .02), with more than doubling (17% to 42%) of imitated acts paired with eye contact in the Interpersonal Synchrony group after the intervention. This skill was generalized to unfamiliar contexts and maintained through follow‐up. Similar gains were observed for initiation of joint attention and shared positive affect, but between‐group differences did not reach statistical significance. A significant time effect was found for all outcomes (p < .001); greatest change occurred during the intervention period, particularly in the Interpersonal Synchrony group. Conclusions: This is the first ASD randomized trial involving toddlers to identify an active ingredient for enhancing socially engaged imitation. Adding social engagement targets to intervention improves short‐term outcome at no additional cost to the intervention. The social, language, and cognitive gains in our participants provide evidence for plasticity of these developmental systems in toddlers with ASD. http://www.clinicaltrials.gov/ct2/show/NCT00106210?term = landa&rank = 3.     

Variability in outcome for children with an ASD diagnosis at age 2

BACKGROUND: Few studies have examined the variability in outcomes of children diagnosed with autism spectrum disorder (ASD) at age 2. Research is needed to understand the children whose symptoms - or diagnoses - change over time. The objectives of this study were to examine the behavioral and diagnostic outcomes of a carefully defined sample of 2-year-old children with ASD, and to identify child and environmental factors that contribute to variability in outcomes at age 4. METHODS: Forty-eight children diagnosed with autism or pervasive developmental disorder not otherwise specified (PDDNOS) at age 2 were followed to age 4. Diagnostic measures included the Autism Diagnostic Observation Schedule - Generic (ADOS-G) and clinical diagnosis at ages 2 and 4, and the ADI-R at age 4. RESULTS: Diagnostic stability for an ASD diagnosis (autism or PDDNOS) was 63%, and for an autism diagnosis was 68%. Children who failed to meet diagnostic criteria for ASD at follow-up were more likely to: 1) be 30 months or younger at initial evaluation; 2) have milder symptoms of autism, particularly in the social domain; and 3) have higher cognitive scores at age 2. No differences between children with stable and unstable diagnoses were found for amount of intervention services received. Among the children with unstable diagnoses, all but one continued to have developmental disorders, most commonly in the area of language. CONCLUSIONS: The stability of ASD was lower in the present study than has been reported previously, a finding largely attributable to children who were diagnosed at 30 months or younger. Implications for clinical practice are discussed.     

Cognitive profiles and social-communicative functioning in children with autism spectrum disorder

BACKGROUND: Whether there is an unusual degree of unevenness in the cognitive abilities of children with autism spectrum disorder (ASD) and whether different cognitive profiles among children with ASD might index etiologically significant subgroups are questions of continued debate in autism research. METHOD: The Differential Ability Scales (DAS) and the Autism Diagnostic Observation Schedule (ADOS) were used to examine profiles of verbal and nonverbal abilities and their relationship to autistic symptomatology in 120 relatively high-functioning children with ADI-confirmed diagnoses of autism. RESULTS: Discrepancies between verbal and nonverbal ability scores occurred at a significantly higher rate than in the DAS normative sample (30%) in both a younger group of 73 children (56%) with a mean age of 5;5 and an older group of 47 children (62%) with a mean age of 8;11. Discrepancies were mainly in favor of nonverbal ability in the younger group, but occurred equally in favor of verbal and nonverbal abilities in the older group. Comparison of the two age groups suggested a growing dissociation between verbal and nonverbal (and particularly visual processing) skills with age. In the older group, children with discrepantly higher nonverbal abilities demonstrated significantly greater impairment in social functioning, as measured on the ADOS, independent of absolute level of verbal and overall ability. CONCLUSIONS: These findings demonstrate a high rate of uneven cognitive development in children with ASD. Indications of a dissociation between verbal and visual-perceptual skills among the older children, and the specific association of discrepantly high nonverbal skills with increased social symptoms suggest that the nonverbal > verbal profile may index an etiologically significant subtype of autism.