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1.  Myeloid dendritic cells frequencies are increased in children with autism spectrum disorder and associated with amygdala volume and repetitive behaviors 
The pathophysiology of Autism Spectrum Disorder (ASD) is not yet known; however, studies suggest that dysfunction of the immune system affects many children with ASD. Increasing evidence points to dysfunction of the innate immune system including activation of microglia and perivascular macrophages, increases in inflammatory cytokines/chemokines in brain tissue and CSF, and abnormal peripheral monocyte cell function. Dendritic cells are major players in innate immunity and have important functions in the phagocytosis of pathogens or debris, antigen presentation, activation of naïve T cells, induction of tolerance and cytokine/chemokine production. In this study, we assessed circulating frequencies of myeloid dendritic cells (defined as Lin-1−BDCA1+CD11c+ and Lin-1−BDCA3+CD123−) and plasmacytoid dendritic cells (Lin-1− BDCA2+CD123+ or Lin-1−BDCA4+ CD11c−) in 57 children with ASD, and 29 typically developing controls of the same age, all of who were enrolled as part of the Autism Phenome Project (APP). The frequencies of dendritic cells and associations with behavioral assessment and MRI measurements of amygdala volume were compared in the same participants. The frequencies of myeloid dendritic cells were significantly increased in children with ASD compared to typically developing controls (p < 0.03). Elevated frequencies of myeloid dendritic cells were positively associated with abnormal right and left amygdala enlargement, severity of gastrointestinal symptoms and increased repetitive behaviors. The frequencies of plasmacytoid dendritic cells were also associated with amygdala volumes as well as developmental regression in children with ASD. Dendritic cells play key roles in modulating immune responses and differences in frequencies or functions of these cells may result in immune dysfunction in children with ASD. These data further implicate innate immune cells in the complex pathophysiology of ASD.
PMCID: PMC4229011  PMID: 23063420
Autism; dendritic cells; repetitive behaviors; amygdala volume; innate immunity
2.  Head Circumferences in Twins With and Without Autism Spectrum Disorders 
To determine the genetic relationship between head circumference (HC) and Autism Spectrum Disorders (ASDs). Twin pairs with at least one twin with an ASD were assessed. HCs in affected and unaffected individuals were compared, as were HC correlations in monozygotic and dizygotic pairs. 404 subjects, ages 4–18, were included. 20 % of males and 27 % of females with an ASD had macrocephaly. Unaffected co-twins showed similar rates (15 % of males and 22 % of females). Statistical analysis revealed no significant difference in HCs between affected and unaffected twins. Twins with ASDs and unaffected co-twins have similar HCs and increased rates of macrocephaly. Correlations demonstrated partial inheritance of HCs. Thus, macrocephaly may represent an endophenotype in ASDs.
PMCID: PMC3732556  PMID: 23321801
Macrocephaly; Head circumference; Twins; Endophenotype; Genetics
3.  Early brain enlargement and elevated extra-axial fluid in infants who develop autism spectrum disorder 
Brain  2013;136(9):2825-2835.
Prospective studies of infants at risk for autism spectrum disorder have provided important clues about the early behavioural symptoms of autism spectrum disorder. Diagnosis of autism spectrum disorder, however, is not currently made until at least 18 months of age. There is substantially less research on potential brain-based differences in the period between 6 and 12 months of age. Our objective in the current study was to use magnetic resonance imaging to identify any consistently observable brain anomalies in 6–9 month old infants who would later develop autism spectrum disorder. We conducted a prospective infant sibling study with longitudinal magnetic resonance imaging scans at three time points (6–9, 12–15, and 18–24 months of age), in conjunction with intensive behavioural assessments. Fifty-five infants (33 ‘high-risk’ infants having an older sibling with autism spectrum disorder and 22 ‘low-risk’ infants having no relatives with autism spectrum disorder) were imaged at 6–9 months; 43 of these (27 high-risk and 16 low-risk) were imaged at 12–15 months; and 42 (26 high-risk and 16 low-risk) were imaged again at 18–24 months. Infants were classified as meeting criteria for autism spectrum disorder, other developmental delays, or typical development at 24 months or later (mean age at outcome: 32.5 months). Compared with the other two groups, infants who developed autism spectrum disorder (n = 10) had significantly greater extra-axial fluid at 6–9 months, which persisted and remained elevated at 12–15 and 18–24 months. Extra-axial fluid is characterized by excessive cerebrospinal fluid in the subarachnoid space, particularly over the frontal lobes. The amount of extra-axial fluid detected as early as 6 months was predictive of more severe autism spectrum disorder symptoms at the time of outcome. Infants who developed autism spectrum disorder also had significantly larger total cerebral volumes at both 12–15 and 18–24 months of age. This is the first magnetic resonance imaging study to prospectively evaluate brain growth trajectories from infancy in children who develop autism spectrum disorder. The presence of excessive extra-axial fluid detected as early as 6 months and the lack of resolution by 24 months is a hitherto unreported brain anomaly in infants who later develop autism spectrum disorder. This is also the first magnetic resonance imaging evidence of brain enlargement in autism before age 2. These findings raise the potential for the use of structural magnetic resonance imaging to aid in the early detection of children at risk for autism spectrum disorder or other neurodevelopmental disorders.
PMCID: PMC3754460  PMID: 23838695
autism; magnetic resonance imaging; infant brain development; cerebrospinal fluid; external hydrocephalus
4.  Behavior and Sleep Problems in Children with a Family History of Autism 
The present study explores behavioral and sleep outcomes in preschool age siblings of children with autism spectrum disorders (ASD). This study focuses on behavior problems that are common in children with ASD, such as emotional reactivity, anxiety, inattention, aggression, and sleep problems. Infant siblings were recruited from families with at least one older child with ASD (high-risk group, n = 104) or families with no history of ASD (low-risk group, n = 76). As part of a longitudinal prospective study, children completed the Mullen Scales of Early Learning and the Autism Diagnostic Observation Schedule, and parents completed the Child Behavior Checklist (CBCL) and the Social Communication Questionnaire at 36 months of age. This study focuses on developmental concerns outside of ASD; therefore, only siblings who did not develop an ASD were included in analyses. Negative binomial regression analyses revealed that children in the high-risk group were more likely to have elevated behavior problems on the CBCL Anxious/Depressed and Aggression subscales. To explore sleep problems as a correlate of these behavior problems, a second series of models was specified. For both groups of children, sleep problems were associated with elevated behavior problems in each of the areas assessed (reactivity, anxiety, somatic complaints, withdrawal, attention, and aggression). These findings support close monitoring of children with a family history of ASD for both behavioral and sleep issues.
PMCID: PMC3947924  PMID: 23436793
autism; siblings; behavior problems; sleep
5.  Beyond Autism: A Baby Siblings Research Consortium Study of High-Risk Children at Three Years of Age 
First-degree relatives of persons with an autism spectrum disorder (ASD) are at increased risk for ASD-related characteristics. As little is known about the early expression of these characteristics, this study characterizes the non-ASD outcomes of 3-year-old high-risk (HR) siblings of children with ASD.
Two groups of children without ASD participated: 507 HR siblings and 324 low-risk (LR) control subjects (no known relatives with ASD). Children were enrolled at a mean age of 8 months, and outcomes were assessed at 3 years. Outcome measures were Autism Diagnostic Observation Schedule (ADOS) calibrated severity scores, and Mullen Verbal and Non-Verbal Developmental Quotients (DQ).
At 3 years, HR siblings without an ASD outcome exhibited higher mean ADOS severity scores and lower verbal and non-verbal DQs than LR controls. HR siblings were over-represented (21% HR versus 7% LR) in latent classes characterized by elevated ADOS severity and/or low to low-average DQs. The remaining HR siblings without ASD outcomes (79%) belonged to classes in which they were not differentially represented with respect to LR siblings.
Having removed a previously identified 18.7% of HR siblings with ASD outcomes from all analyses, HR siblings nevertheless exhibited higher mean levels of ASD severity and lower levels of developmental functioning than LR children. However, the latent class membership of four-fifths of the HR siblings was not significantly different from that of LR control subjects. One-fifth of HR siblings belonged to classes characterized by higher ASD severity and/or lower levels of developmental functioning. This empirically derived characterization of an early-emerging pattern of difficulties in a minority of 3-year-old HR siblings suggests the importance of developmental surveillance and early intervention for these children.
PMCID: PMC3625370  PMID: 23452686
ASD; high-risk siblings; outcome; broad autism phenotype
6.  Is Maternal Influenza or Fever During Pregnancy Associated with Autism or Developmental Delays? Results from the CHARGE (CHildhood Autism Risks from Genetics and Environment) Study 
We analyzed data from case groups of 538 children with autism spectrum disorders (ASD) and 163 with developmental delays (DD), and from 421 typically developing controls to assess associations with maternal influenza or fever during pregnancy. Exposure information was obtained by telephone interviews, and outcomes were clinically confirmed. Though neither ASD nor DD was associated with influenza, both were associated with maternal fever during pregnancy: OR’s (odds ratios) were 2.12 (95 % CI 1.17, 3.84) and 2.50 (95 % CI 1.20, 5.20) respectively. However, the fever-associated ASD risk was attenuated among mothers who reported taking antipyretic medications (OR = 1.30, 95 % CI 0.59, 2.84), but remained elevated for those who did not (OR = 2.55, 95 % CI 1.30, 4.99).
PMCID: PMC3484245  PMID: 22562209
Maternal influenza; Fever; Autism; Anti-fever medication
7.  Imitation from 12 to 24 months in autism and typical development: A longitudinal Rasch analysis 
Developmental psychology  2011;47(6):1565-1578.
The development of imitation during the second year of life plays an important role in domains of socio-cognitive development such as language and social learning. Deficits in imitation ability in persons with autism spectrum disorder (ASD) have also been repeatedly documented from toddlerhood into adulthood, raising the possibility that early disruptions in imitation contribute to the onset of ASD and the deficits in language and social interaction that define the disorder. This study prospectively examined the development of imitation between 12 and 24 months of age in 154 infants at familial risk for ASD and 78 typically developing infants who were all later assessed at 36 months for ASD or other developmental delays. The study established a developmental measure of imitation ability, and examined group differences over time, using an analytic Rasch measurement model. Results revealed a unidimensional latent construct of imitation and verified a reliable sequence of imitation skills that was invariant over time for all outcome groups. Results also showed that all groups displayed similar significant linear increases in imitation ability between 12 and 24 months and that these increases were related to individual growth in both expressive language and ratings of social engagement, but not fine motor development. The group of children who developed ASD by age 3 years exhibited delayed imitation development compared to the low-risk typical outcome group across all time-points, but were indistinguishable from other high-risk infants who showed other cognitive delays not related to ASD.
PMCID: PMC3712626  PMID: 21910524
imitation; autism; Rasch analysis; early identification; HGLM
8.  Onset patterns in autism: Correspondence between home video and parent report 
The onset of autism is usually conceptualized as occurring in one of two patterns, an early onset and a regressive pattern. This study examined the number and shape of trajectories of symptom onset evident in coded home movies of children with autism and examined their correspondence with parent report of onset.
Four social-communicative behaviors were coded from the home video of children with autism (n = 52) or typical development (n = 23). All home video from 6 through 24 months of age was coded (3199 segments). Latent class modeling was used to characterize trajectories and determine the optimal number needed to describe the coded home video. These trajectories were then compared to parent report of onset patterns, as defined by the Autism Diagnostic Interview-Revised.
A three trajectory model best fit the data from the participants with autism. One trajectory displayed low levels of social-communication across time. A second trajectory displayed high levels of social-communication early in life, followed by a significant decline over time. A third trajectory displayed initial levels of behavior that were similar to the typically developing group, but little progress in social-communication with age. There was poor correspondence between home video-based trajectories and parent report of onset.
More than two onset categories may be needed to describe the ways in which symptoms emerge in children with autism. There is low agreement between parent report and home video, suggesting that methods for improving parent report of early development must be developed.
PMCID: PMC3668453  PMID: 21784299
Autism; regression; onset; parent report
9.  Maternal Metabolic Conditions and Risk for Autism and Other Neurodevelopmental Disorders 
Pediatrics  2012;129(5):e1121-e1128.
We examined whether metabolic conditions (MCs) during pregnancy (diabetes, hypertension, and obesity) are associated with autism spectrum disorder (ASD), developmental delays (DD), or impairments in specific domains of development in the offspring.
Children aged 2 to 5 years (517 ASD, 172 DD, and 315 controls) were enrolled in the CHARGE (Childhood Autism Risks from Genetics and the Environment) study, a population-based, case-control investigation between January 2003 and June 2010. Eligible children were born in California, had parents who spoke English or Spanish, and were living with a biological parent in selected regions of California. Children’s diagnoses were confirmed by using standardized assessments. Information regarding maternal conditions was ascertained from medical records or structured interview with the mother.
All MCs were more prevalent among case mothers compared with controls. Collectively, these conditions were associated with a higher likelihood of ASD and DD relative to controls (odds ratio: 1.61 [95% confidence interval: 1.10–2.37; odds ratio: 2.35 [95% confidence interval: 1.43–3.88], respectively). Among ASD cases, children of women with diabetes had Mullen Scales of Early Learning (MSEL) expressive language scores 0.4 SD lower than children of mothers without MCs (P < .01). Among children without ASD, those exposed to any MC scored lower on all MSEL and Vineland Adaptive Behavior Scales (VABS) subscales and composites by at least 0.4 SD (P < .01 for each subscale/composite).
Maternal MCs may be broadly associated with neurodevelopmental problems in children. With obesity rising steadily, these results appear to raise serious public health concerns.
PMCID: PMC3340592  PMID: 22492772
autism; developmental delay; diabetes; epidemiology; hypertension; obesity
10.  Recurrence Risk for Autism Spectrum Disorders: A Baby Siblings Research Consortium Study 
Pediatrics  2011;128(3):e488-e495.
The recurrence risk of autism spectrum disorders (ASD) is estimated to be between 3% and 10%, but previous research was limited by small sample sizes and biases related to ascertainment, reporting, and stoppage factors. This study used prospective methods to obtain an updated estimate of sibling recurrence risk for ASD.
A prospective longitudinal study of infants at risk for ASD was conducted by a multisite international network, the Baby Siblings Research Consortium. Infants (n = 664) with an older biological sibling with ASD were followed from early in life to 36 months, when they were classified as having or not having ASD. An ASD classification required surpassing the cutoff of the Autism Diagnostic Observation Schedule and receiving a clinical diagnosis from an expert clinician.
A total of 18.7% of the infants developed ASD. Infant gender and the presence of >1 older affected sibling were significant predictors of ASD outcome, and there was an almost threefold increase in risk for male subjects and an additional twofold increase in risk if there was >1 older affected sibling. The age of the infant at study enrollment, the gender and functioning level of the infant's older sibling, and other demographic factors did not predict ASD outcome.
The sibling recurrence rate of ASD is higher than suggested by previous estimates. The size of the current sample and prospective nature of data collection minimized many limitations of previous studies of sibling recurrence. Clinical implications, including genetic counseling, are discussed.
PMCID: PMC3164092  PMID: 21844053
autism; recurrence; sibling risk
11.  Brief Report: Symptom Onset Patterns and Functional Outcomes in Young Children with Autism Spectrum Disorders 
This study examined the relationship between onset status and current functioning using a recently proposed onset classification system in 272 young children with autism spectrum disorder (ASD). Participants were classified into one of the following groups, based on parent report using the Autism Diagnostic Interview – Revised: Early Onset (symptoms by 12 months, no loss), Delay+Regression (symptoms by 12 months plus loss), Plateau (no early symptoms or loss), and Regression (no early symptoms, followed by loss). Findings indicate that current functioning does not differ according to onset pattern, calling into question the use of onset categorizations for prognostic purposes in children with ASD.
PMCID: PMC3265105  PMID: 21360021
autism; regression; onset; symptom; outcomes
12.  Infant siblings and the investigation of autism risk factors 
Infant sibling studies have been at the vanguard of autism spectrum disorders (ASD) research over the past decade, providing important new knowledge about the earliest emerging signs of ASD and expanding our understanding of the developmental course of this complex disorder. Studies focused on siblings of children with ASD also have unrealized potential for contributing to ASD etiologic research. Moving targeted time of enrollment back from infancy toward conception creates tremendous opportunities for optimally studying risk factors and risk biomarkers during the pre-, peri- and neonatal periods. By doing so, a traditional sibling study, which already incorporates close developmental follow-up of at-risk infants through the third year of life, is essentially reconfigured as an enriched-risk pregnancy cohort study. This review considers the enriched-risk pregnancy cohort approach of studying infant siblings in the context of current thinking on ASD etiologic mechanisms. It then discusses the key features of this approach and provides a description of the design and implementation strategy of one major ASD enriched-risk pregnancy cohort study: the Early Autism Risk Longitudinal Investigation (EARLI).
PMCID: PMC3436647  PMID: 22958474
Autism; Cohort; Epidemiology; Pregnancy; Prospective; Sibling; Study Design
13.  How does the topic of conversation affect verbal exchange and eye gaze? A comparison between typical development and high-functioning autism 
Neuropsychologia  2010;48(9):2730-2739.
Conversation is a primary area of difficultly for individuals with high-functioning autism (HFA) although they have unimpaired formal language abilities. This likely stems from the unstructured nature of face-to-face conversation as well as the need to coordinate other modes of communication (e.g. eye gaze) with speech. We conducted a quantitative analysis of both verbal exchange and gaze data obtained from conversations between children with HFA and an adult, compared with those of typically-developing children matched on language level. We examined a new question: How does speaking about a topic of interest affect reciprocity of verbal exchange and eye gaze? Conversations on generic topics were compared with those on individuals’ circumscribed interests, particularly intense interests characteristic of HFA. Two opposing hypotheses were evaluated. Speaking about a topic of interest may improve reciprocity in conversation by increasing participants’ motivation and engagement. Alternatively, it could engender more one-sided interaction, given the engrossing nature of circumscribed interests. In their verbal exchanges HFA participants demonstrated decreased reciprocity during the interest topic, evidenced by fewer contingent utterances and more monologue-style speech. Moreover, a measure of stereotyped behaviour and restricted interest symptoms was inversely related to reciprocal verbal exchange. However, both the HFA and comparison groups looked significantly more to their partner’s face during the interest than generic topic. Our interpretation of results across modalities is that circumscribed interests led HFA participants to be less adaptive to their partner verbally, but speaking about a highly practiced topic allowed for increased gaze to the partner. The function of this increased gaze to partner may differ for the HFA and comparison groups.
PMCID: PMC2935904  PMID: 20493890
conversation; high-functioning autism; eye-gaze; circumscribed interests; restricted and repetitive behaviours
14.  The Neural Substrates of Cognitive Control Deficits in Autism Spectrum Disorders 
Neuropsychologia  2009;47(12):2515-2526.
Executive functions deficits are among the most frequently reported symptoms of autism spectrum disorders (ASDs), however, there have been few functional magnetic resonance imaging (fMRI) studies that investigate the neural substrates of executive functions deficits in ASDs, and only one in adolescents. The current study examined cognitive control –the ability to maintain task context online to support adaptive functioning in the face of response competition—in 22 adolescents aged 12–18 with autism spectrum disorders and 23 age, gender, and IQ matched typically developing subjects. During the cue phase of the task, where subjects must maintain information online to overcome a prepotent response tendency, typically developing subjects recruited significantly more anterior frontal (BA 10), parietal (BA 7, 40), and occipital regions (BA 18) for high control trials (25% of trials) versus low control trials (75% of trials). Both groups showed similar activation for low control cues, however the ASD group exhibited significantly less activation for high control cues. Functional connectivity analysis using time series correlation, factor analysis, and beta series correlation methods provided convergent evidence that the ASD group exhibited lower levels of functional connectivity and less network integration between frontal, parietal, and occipital regions. In the typically developing group, fronto-parietal connectivity was related to lower error rates on high control trials. In the autism group, reduced fronto-parietal connectivity was related to attention deficit hyperactivity disorder symptoms.
PMCID: PMC2766616  PMID: 19410583
autism spectrum disorders; cognitive control; executive functions; fMRI; functional connectivity; attention deficit disorder
15.  Common genetic variants on 5p14.1 associate with autism spectrum disorders 
Nature  2009;459(7246):528-533.
Autism spectrum disorders (ASDs) represent a group of childhood neurodevelopmental and neuropsychiatric disorders characterized by deficits in verbal communication, impairment of social interaction, and restricted and repetitive patterns of interests and behaviour. To identify common genetic risk factors underlying ASDs, here we present the results of genome-wide association studies on a cohort of 780 families (3,101 subjects) with affected children, and a second cohort of 1,204 affected subjects and 6,491 control subjects, all of whom were of European ancestry. Six single nucleotide polymorphisms between cadherin 10 (CDH10) and cadherin 9 (CDH9)—two genes encoding neuronal cell-adhesion molecules—revealed strong association signals, with the most significant SNP being rs4307059 (P = 3.4 × 10−8, odds ratio = 1.19). These signals were replicated in two independent cohorts, with combined P values ranging from 7.4 × 10−8 to 2.1 × 10−10. Our results implicate neuronal cell-adhesion molecules in the pathogenesis of ASDs, and represent, to our knowledge, the first demonstration of genome-wide significant association of common variants with susceptibility to ASDs.
PMCID: PMC2943511  PMID: 19404256
16.  Deferred and immediate imitation in regressive and early onset autism 
Deferred imitation has long held a privileged position in early cognitive development, considered an early marker of representational thought with links to language development and symbolic processes. Children with autism have difficulties with several abilities generally thought to be related to deferred imitation: immediate imitation, language, and symbolic play. However, few studies have examined deferred imitation in early autism. The present study examined both deferred, spontaneous imitation and immediate, elicited imitation on a set of carefully matched tasks in 36 young children with autism: 16 with early onset autism, 20 with regressive autism and two contrast groups, younger typically developing children (n = 20) and age matched children with significant developmental delays (n = 21). Analyses of co-variance controlling for differences in verbal mental age revealed significant main effects for task, but no main effect of group and no interaction of task by group. Deferred imitation scores were lower than immediate imitation scores for all groups. Imitation performance was related to overall intellectual functioning for all groups, and there were moderate and significant relations between imitation in the immediate elicited condition and in the spontaneous deferred condition for all groups. Finally, there were no differences between onset subgroups in imitation scores, suggesting that the two share a similar phenotype involving both types of imitation.
PMCID: PMC2940420  PMID: 18221343
Autistic disorder; development; developmental delay; mental retardation; pervasive developmental disorder; preschool children; imitation
17.  Imitating actions on objects in early-onset and regressive autism: Effects and implications of task characteristics on performance 
This study was designed to examine the nature of object imitation performance in early autism. We hypothesized that imitation would be relatively preserved when behaviors on objects resulted in salient instrumental effects. We designed tasks in which, in one condition, the motor action resulted in a salient, meaningful effect on an object, whereas in the other condition, the same action resulted in a less salient effect because of differing object characteristics. The motor aspects of the tasks did not vary across conditions. Four participant groups of 2- to 5-year-olds were examined: 17 children with early-onset autism, 24 children with regressive onset autism, 22 children with developmental delays, and 22 children with typical development. Groups were matched on nonverbal skills, and differences in verbal development were examined as a moderator of imitative ability. Results revealed an interaction of group by condition, with the combined autism group failing more tasks than the combined comparison groups, and failing more tasks in the less salient condition than in the more salient condition, as hypothesized. Analyses of autism subgroups revealed these effects were primarily because of the regression onset group. Accuracy of motor performance was examined by analyzing errors. Among children passing imitative acts, there were no group differences and no condition effects in the number, type, or pattern of performance errors. Among children passing the tasks, the group with autism did not demonstrate more emulation errors (imitating the goal but not the means) than other groups. There was no evidence that either motor or attentional aspects of the tasks contributed to the poorer imitative performance of the children with autism.
PMCID: PMC2940421  PMID: 20102648
18.  Gaze Behavior and Affect at 6-Months: Predicting Clinical Outcomes and Language Development in Typically Developing Infants and Infants At-Risk for Autism 
Developmental science  2009;12(5):798-814.
This paper presents follow-up longitudinal data to research that previously suggested the possibility of abnormal gaze behavior marked by decreased eye contact in a subgroup of 6-month-old infants at risk for autism (Merin et al., 2007). Using eye-tracking data and behavioral data recorded during a live mother-infant interaction involving the still-face procedure, the predictive utility of gaze behavior and affective behaviors at 6 months was examined using diagnostic outcome data obtained longitudinally over the following 18 months. Results revealed that none of the infants previously identified as showing lower rates of eye-contact had any signs of autism at outcome. In contrast, three infants who were diagnosed with autism demonstrated consistent gaze to the eye region and typical affective responses at 6 months. Individual differences in face scanning and affective responsivity during the live interaction were not related to any continuous measures of symptom frequency or symptom severity. In contrast, results of growth curve models for language development revealed significant relationships between face scanning and expressive language. Greater amounts of fixation to the mother’s mouth during live interaction predicted higher levels of expressive language at outcome and greater rates of growth. These findings suggest that although gaze behavior at 6 months may not provide early markers for autism as initially conceived, gaze to the mouth in particular may be useful in predicting individual differences in language development.
PMCID: PMC2732664  PMID: 19702771
autism; eye tracking; language development; early identification; speech perception
19.  A Prospective Study of the Emergence of Early Behavioral Signs of Autism 
To examine prospectively the emergence of behavioral signs of autism in the first years of life in infants at low and high risk for autism.
A prospective longitudinal design was used to compare 25 infants later diagnosed with an autism spectrum disorder (ASD) with 25 gender-matched low-risk children later determined to have typical development. Participants were evaluated at 6, 12, 18, 24, and 36 months of age. Frequencies of gaze to faces, social smiles, and directed vocalizations were coded from video and rated by examiners.
The frequency of gaze to faces, shared smiles, and vocalizations to others were highly comparable between groups at 6 months of age, but significantly declining trajectories over time were apparent in the group later diagnosed with ASD. Group differences were significant by 12 months of age on most variables. Although repeated evaluation documented loss of skills in most infants with ASD, most parents did not report a regression in their child’s development.
These results suggest that behavioral signs of autism are not present at birth, as once suggested by Kanner, but emerge over time through a process of diminishment of key social communication behaviors. More children may present with a regressive course than previously thought, but parent report methods do not capture this phenomenon well. Implications for onset classification systems and clinical screening are also discussed.
PMCID: PMC2923050  PMID: 20410715
Autism; Onset; Infancy; Regression
20.  Atypical object exploration at 12 months of age is associated with autism in a prospective sample 
This prospective study examined object exploration behavior in 66 12-month-old infants, of whom nine were subsequently diagnosed with an autism spectrum disorder. Previous investigations differ on when the repetitive behaviors characteristic of autism are first present in early development. A task was developed that afforded specific opportunities for a range of repetitive uses of objects and was coded blind to outcome status. The autism/ASD outcome group displayed significantly more spinning, rotating, and unusual visual exploration of objects than two comparison groups. The average unusual visual exploration score of the autism/ASD group was over four standard deviations above the mean of the group with no concerns at outcome. Repetitive behaviors at 12 months were significantly related to cognitive and symptomatic status at 36 month outcome. These results suggest that repetitive or stereotyped behaviors may be present earlier than initially thought in very young children developing the autism phenotype.
PMCID: PMC2921192  PMID: 18805942
autism; diagnosis; early identification; repetitive behavior
21.  How Early Do Parent Concerns Predict Later Autism Diagnosis? 
To study the relationship between parent concerns about development in the first year and a half of life and later autism diagnostic outcomes.
Parent concerns about development were collected for infants at high and low risk for autism, using a prospective, longitudinal design. Parents were asked about developmental concerns at study intake and when their infant was 6, 12, and 18 months. Infants were then followed up until 36 months, when diagnostic status was determined.
By the time their child was 12 months, parents who have an older child with autism reported significantly more concerns in autism spectrum disorders-related areas than parents of children with typical outcomes. These concerns were significantly related to independent measures of developmental status and autism symptoms and helped predict which infants would later be diagnosed with autism or autism spectrum disorders. At 6 months, however, the concerns of parents who have an older child with autism do not predict outcome well.
Explicitly probing for parent concerns about development is useful for identifying children in need of closer monitoring and surveillance, as recommended by the American Academy of Pediatrics.
PMCID: PMC2919345  PMID: 19827218
22.  Behavioral Profiles of Affected and Unaffected Siblings of Children with Autism: Contribution of Measures of Mother–Infant Interaction and Nonverbal Communication 
We investigated whether deficits in social gaze and affect and in joint attention behaviors are evident within the first year of life among siblings of children with autism who go on to be diagnosed with autism or ASD (ASD) and siblings who are non-diagnosed (NoASD-sib) compared to low-risk controls. The ASD group did not differ from the other two groups at 6 months of age in the frequency of gaze, smiles, and vocalizations directed toward the caregiver, nor in their sensitivity to her withdrawal from interaction. However, by 12 months, infants in the ASD group exhibited lower rates of joint attention and requesting behaviors. In contrast, NoASD-sibs did not differ from comparison infants on any variables of interest at 6 and 12 months.
PMCID: PMC3044086  PMID: 20568002
Autism; Broader autism phenotype; Early identification; Mother–infant interaction; Still face procedure; Nonverbal communication
23.  Examining executive functioning in children with autism spectrum disorder, attention deficit hyperactivity disorder and typical development 
Psychiatry research  2009;166(2-3):210-222.
Executive functioning (EF) is an overarching term that refers to neuropsychological processes that enable physical, cognitive, and emotional self-control. Deficits in EF are often present in neurodevelopmental disorders, but the specificity of EF deficits and direct comparison across disorders is rare. The current study investigated EF in 7 to 12 year old children with autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and typical development using a comprehensive battery of measures assessing EF, including response inhibition, working memory, cognitive flexibility, planning, fluency and vigilance. The ADHD group exhibited deficits in vigilance, inhibition and working memory relative to the typical group; however, they did not consistently demonstrate problems on the remaining EF measures. Children with ASD showed significant deficits in vigilance compared to the typical group, and significant differences in response inhibition, cognitive flexibility/switching, and working memory compared to both groups. These results lend support for previous findings that show children with autism demonstrate generalized and profound impairment in EF. In addition, the observed deficits in vigilance and inhibitory control suggest that a significant number of children with ASD present with cognitive profiles consistent with ADHD.
PMCID: PMC2683039  PMID: 19285351
attention; inhibition; comorbidity; working memory; CANTAB; IVA; vigilance
24.  The Onset of Autism: Patterns of Symptom Emergence in the First Years of Life 
Previous conceptualizations of autism have suggested that symptoms are evident either early in the first year of life or later in the second year, after a loss of previously acquired skills. New research suggests, however, that these two patterns do not capture all the different ways autism can emerge. For example, some children show a developmental plateau marked by failure to progress, while other children display mixed features, with both early delays and later losses evident. This paper reviews the literature on autism onset, discusses problems with the traditional ways in which onset has been conceptualized, and provides recommendations for future research. We suggest that onset is better thought of as a dimensional process rather than dichotomous categories.
PMCID: PMC2857525  PMID: 19360687
Onset; regression; infancy; early identification
25.  Clinical Assessment and Management of Toddlers With Suspected Autism Spectrum Disorder: Insights From Studies of High-Risk Infants 
Pediatrics  2009;123(5):1383-1391.
With increased public awareness of the early signs and recent American Academy of Pediatrics recommendations that all 18- and 24-month-olds be screened for autism spectrum disorders, there is an increasing need for diagnostic assessment of very young children. However, unique challenges exist in applying current diagnostic guidelines for autism spectrum disorders to children under the age of 2 years. In this article, we address challenges related to early detection, diagnosis, and treatment of autism spectrum disorders in this age group. We provide a comprehensive review of findings from recent studies on the early development of children with autism spectrum disorders, summarizing current knowledge on early signs of autism spectrum disorders, the screening properties of early detection tools, and current best practice for diagnostic assessment of autism spectrum disorders before 2 years of age. We also outline principles of effective intervention for children under the age of 2 with suspected/confirmed autism spectrum disorders. It is hoped that ongoing studies will provide an even stronger foundation for evidence-based diagnostic and intervention approaches for this critically important age group.
PMCID: PMC2833286  PMID: 19403506
autism; early detection; toddlers; longitudinal studies; child development

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