Biomedical subjects

Geraldine Dawson

Publications and source records attributed to Geraldine Dawson.

At least 19 recordsLinked to original sources

PubMed2007

Early social, imitation, play, and language abilities of young non-autistic siblings of children with autism.

Studies are needed to better understand the broad autism phenotype in young siblings of children with autism. Cognitive, adaptive, social, imitation, play, and language abilities were examined in 42 non-autistic siblings and 20 toddlers with no family history of autism, ages 18-27 months. Siblings, as a group, were below average in expressive language and composite IQ, had lower mean receptive language, adaptive behavior, and social communication skills, and used fewer words, distal gestures, and responsive social smiles than comparison children. Additionally, parents reported social impairments in siblings by 13 months of age. These results suggest that the development of young non-autistic siblings is affected at an early age and, thus, should be closely monitored, with appropriate interventions implemented as needed.

Adaptation, Psychological↗

PubMed2007

Designing research studies on psychosocial interventions in autism.

To address methodological challenges in research on psychosocial interventions for autism spectrum disorder (ASD), a model was developed for systematically validating and disseminating interventions in a sequence of steps. First, initial efficacy studies are conducted to establish interventions as promising. Next, promising interventions are assembled into a manual, which undergoes pilot-testing. Then, randomized clinical trials test efficacy under controlled conditions. Finally, effectiveness studies evaluate outcomes in community settings. Guidelines for research designs at each step are presented. Based on the model, current priorities in ASD research include (a) preparation for efficacy and effectiveness trials by developing manuals for interventions that have shown promise and (b) initial efficacy studies on interventions for core features of ASD such as social reciprocity.

Autistic Disorder↗

PubMed2007

Quantitative assessment of autism symptom-related traits in probands and parents: Broader Phenotype Autism Symptom Scale.

Autism susceptibility genes likely have effects on continuously distributed autism-related traits, yet few measures of such traits exist. The Broader Phenotype Autism Symptom Scale (BPASS), developed for use with affected children and family members, measures social motivation, social expressiveness, conversational skills, and flexibility. Based on 201 multiplex families, psychometric data on the BPASS are reported. Adequate inter-rater reliability and internal consistency were found. Parents had lower BPASS scores than affected children, after controlling for IQ. Parents and affected children showed overlapping distributions suggesting the BPASS captured variability in traits across groups. BPASS scores were not correlated with ethnicity or parent education; however, some domains were correlated with IQ. The BPASS holds promise as a quantitative phenotypic assessment for genetic studies.

Autistic Disorder↗

PubMed2006

Rate of head growth decelerates and symptoms worsen in the second year of life in autism.

BACKGROUND: Longitudinal studies of head circumference growth in infants later diagnosed with autism are needed to understand the accelerated head growth in this disorder. METHODS: We analyzed longitudinal head circumference data from birth to 3 years in 28 children later diagnosed with autism spectrum disorder on the basis of individual growth curve analyses using hierarchical linear models. RESULTS: Head circumference Z scores relative to norms significantly increased in the autism sample from birth to 12 months, but this pattern did not persist beyond 12 months. Rather, the rate of change in head circumference from 12 to 36 months was not different from the normative sample. CONCLUSIONS: These results suggest that a period of exceptionally rapid head growth occurs during the first year of life in autism; after 12 months of age, the rate of head circumference growth decelerates relative to the rate during the first year of life. Studies of behavioral development in infants later diagnosed with autism suggest that the period of acceleration of head growth precedes and overlaps with the onset of behavioral symptoms, and the period of deceleration coincides with a period of worsening of symptoms in the second year of life.

Age Factors↗

PubMed2006

Head circumference and height in autism: a study by the Collaborative Program of Excellence in Autism.

Data from 10 sites of the NICHD/NIDCD Collaborative Programs of Excellence in Autism were combined to study the distribution of head circumference and relationship to demographic and clinical variables. Three hundred thirty-eight probands with autism-spectrum disorder (ASD) including 208 probands with autism were studied along with 147 parents, 149 siblings, and typically developing controls. ASDs were diagnosed, and head circumference and clinical variables measured in a standardized manner across all sites. All subjects with autism met ADI-R, ADOS-G, DSM-IV, and ICD-10 criteria. The results show the distribution of standardized head circumference in autism is normal in shape, and the mean, variance, and rate of macrocephaly but not microcephaly are increased. Head circumference tends to be large relative to height in autism. No site, gender, age, SES, verbal, or non-verbal IQ effects were present in the autism sample. In addition to autism itself, standardized height and average parental head circumference were the most important factors predicting head circumference in individuals with autism. Mean standardized head circumference and rates of macrocephaly were similar in probands with autism and their parents. Increased head circumference was associated with a higher (more severe) ADI-R social algorithm score. Macrocephaly is associated with delayed onset of language. Although mean head circumference and rates of macrocephaly are increased in autism, a high degree of variability is present, underscoring the complex clinical heterogeneity of the disorder. The wide distribution of head circumference in autism has major implications for genetic, neuroimaging, and other neurobiological research.

Adolescent↗

PubMed2006

Amygdalar volume and behavioral development in autism.

CONTEXT: The amygdala is associated with socioemotional function and has been implicated in the pathophysiology of autism. OBJECTIVE: To examine the relationship between amygdalar volume at ages 3 and 4 years and severity of clinical course and outcome at 6 years of age in children with autism spectrum disorder. DESIGN: Magnetic resonance images acquired at 3 and 4 years of age were used to measure total cerebral, amygdalar, and hippocampal volumes. Acquisition of social and communication skills was assessed semiannually using the Vineland Adaptive Behavior Scales. Hierarchical linear models were used to predict variability in individual linear growth trajectories as a function of IQ, total cerebral, and amygdalar or hippocampal volumes. SETTING: Longitudinal study of children with autism spectrum disorder. PARTICIPANTS: Forty-five children with autism spectrum disorders between 3 and 6 years of age. MAIN OUTCOME MEASURE: Linear growth trajectory of age equivalence Vineland communication and social scores. RESULTS: Larger right amygdalar volume was associated with more severe social and communication impairments at ages 3 and 4 years. Larger right amygdalar volume also was predictive of poorer social and communication abilities at age 6 years, even after controlling for IQ and total cerebral volume. Parallel analyses with hippocampal volumes found no relationship to social or communication development. CONCLUSIONS: Larger right amygdalar volume at 3 and 4 years of age, but not left amygdalar, hippocampal, or total cerebral volume, is associated with a more severe clinical course and worse outcome at age 6 years in children with autism spectrum disorder. These results provide additional evidence that amygdalar development is implicated in the behavioral impairments found in autism.

Amygdala↗

PubMed2006

Gray and white matter brain chemistry in young children with autism.

CONTEXT: The brain pathophysiological abnormalities underlying autism remain unclear. Neuroimaging and histological studies suggest cellular abnormalities early in the course of the disease. OBJECTIVE: To measure the in vivo chemical profile of gray and white matter tissues in autism. DESIGN: Cross-sectional spectroscopic imaging study comparing 3- to 4-year-old children with autism spectrum disorder (ASD) with age-matched comparison groups of children with delayed development (DD) and typical development (TD). SETTING: The University of Washington Diagnostic Imaging Sciences Center, Seattle. PARTICIPANTS: Forty-five 3- to 4-year-old children with ASD, 12 age-matched children with DD, and 10 age-matched children with TD. MAIN OUTCOME MEASURES: Estimates of gray and white matter concentrations for choline-containing compounds (Cho), creatine plus phosphocreatine, N-acetylaspartate (NAA), and myo-inositol (mI). Transverse relaxation times for Cho, creatine plus phosphocreatine, and NAA expressed relative to control subjects with TD were examined to evaluate tissue compactness. RESULTS: The children with ASD demonstrated decreased gray matter concentrations of Cho (P < .001), creatine plus phosphocreatine (P = .02), NAA (P = .02), and mI (P = .008) compared with children with TD. Gray matter Cho transverse relaxation was also prolonged for the ASD sample compared with the TD group (P = .01). The children with ASD demonstrated significantly decreased levels of Cho (P = .04) and mI (P = .008) and trend-level NAA (P = .09) in gray matter compared with the DD group. For white matter, both children with ASD and children with DD showed a similar pattern of NAA and mI level decreases (for children with ASD vs children with TD: NAA, P = .03; mI, P = .04; for children with DD vs children with TD, NAA, P = .03; mI, P = .07). In several analyses, cerebral volume contributed significantly as a covariate. CONCLUSIONS: Reduced gray matter chemical concentrations and altered Cho transverse relaxation, in a pattern distinct from that in children with DD, suggest decreased cellularity, or density, at this early time point in ASD. Possibly reflecting shared developmental features, white matter results were common to ASD and DD groups. The relationship between cerebral volume and neurochemistry at this early time point may indicate processes related to unit scaling.

Aspartic Acid↗

PubMed2006

Is there a 'regressive phenotype' of Autism Spectrum Disorder associated with the measles-mumps-rubella vaccine? A CPEA Study.

A multi-site study of 351 children with Autism Spectrum Disorders (ASD) and 31 typically developing children used caregiver interviews to describe the children's early acquisition and loss of social-communication milestones. For the majority of children with ASD who had experienced a regression, pre-loss development was clearly atypical. Children who had lost skills also showed slightly poorer outcomes in verbal IQ and social reciprocity, a later mean age of onset of autistic symptoms, and more gastrointestinal symptoms than children with ASD and no regression. There was no evidence that onset of autistic symptoms or of regression was related to measles-mumps-rubella vaccination. The implications of these findings for the existence of a 'regressive phenotype' of ASD are discussed.

Autistic Disorder↗

PubMed2006

Familial autoimmune thyroid disease as a risk factor for regression in children with Autism Spectrum Disorder: a CPEA Study.

A multicenter study of 308 children with Autism Spectrum Disorder (ASD) was conducted through the Collaborative Programs of Excellence in Autism (CPEA), sponsored by the National Institute of Child Health and Human Development, to compare the family history of autoimmune disorders in children with ASD with and without a history of regression. A history of regression was determined from the results of the Autism Diagnostic Interview-Revised (ADI-R). Family history of autoimmune disorders was obtained by telephone interview. Regression was significantly associated with a family history of autoimmune disorders (adjusted OR=1.89; 95% CI: 1.17, 3.10). The only specific autoimmune disorder found to be associated with regression was autoimmune thyroid disease (adjusted OR=2.09; 95% CI: 1.28, 3.41).

Autistic Disorder↗

PubMed2006

Corpus callosum morphometrics in young children with autism spectrum disorder.

This study assessed midsagittal corpus callosum cross sectional areas in 3-4 year olds with autism spectrum disorder (ASD) compared to typically developing (TD) and developmentally delayed (DD) children. Though not different in absolute size compared to TD, ASD callosums were disproportionately small adjusted for increased ASD cerebral volume. ASD clinical subgroup analysis revealed greater proportional callosum reduction in the more severely affected autistic disorder (AD) than in pervasive developmental disorder-not otherwise specified (PDD-NOS) children. DD children had smaller absolute callosums than ASD and TD. Subregion analysis revealed widely distributed callosum differences between ASD and TD children. Results could reflect decreased inter-hemispheric connectivity or cerebral enlargement due to increase in tissues less represented in the corpus callosum in ASD.

Analysis of Variance↗

PubMed2006

ERP evidence of atypical face processing in young children with autism.

Autism involves a basic impairment in social cognition. This study investigated early stage face processing in young children with autism by examining the face-sensitive early negative event-related brain potential component in 3-4 year old children with autism spectrum disorder (ASD), typical development, and developmental delay. Results indicated that children with ASD showed a slower electrical brain response to faces and a larger amplitude response to objects compared to children with typical development and developmental delay. These findings indicate that children with ASD have a disordered pattern of brain responses to faces and objects at an early age.

Autistic Disorder↗

PubMed2006

Early predictors of communication development in young children with autism spectrum disorder: joint attention, imitation, and toy play.

This study investigated the unique contributions of joint attention, imitation, and toy play to language ability and rate of development of communication skills in young children with autism spectrum disorder (ASD). Sixty preschool-aged children with ASD were assessed using measures of joint attention, imitation, toy play, language, and communication ability. Two skills, initiating protodeclarative joint attention and immediate imitation, were most strongly associated with language ability at age 3-4 years, whereas toy play and deferred imitation were the best predictors of rate of communication development from age 4 to 6.5 years. The implications of these results for understanding the nature and course of language development in autism and for the development of targeted early interventions are discussed.

Attention↗

PubMed2006

Event-related potential (ERP) indices of infants' recognition of familiar and unfamiliar objects in two and three dimensions.

We measured infants' recognition of familiar and unfamiliar 3-D objects and their 2-D representations using event-related potentials (ERPs). Infants differentiated familiar from unfamiliar objects when viewing them in both two and three dimensions. However, differentiation between the familiar and novel objects occurred more quickly when infants viewed the object in 3-D than when they viewed 2-D representations. The results are discussed with respect to infants' recognition abilities and their understanding of real objects and representations. This is the first study using 3-D objects in conjunction with ERPs in infants, and it introduces an interesting new methodology for assessing infants' electrophysiological responses to real objects.

Child Development↗

PubMed2005

Validation of the phenomenon of autistic regression using home videotapes.

CONTEXT: To date, there has been no objective validation of the phenomenon of autistic regression early in life. OBJECTIVE: To validate parental report of autistic regression using behavioral data coded from home videotapes of children with autism spectrum disorder (ASD) vs typical development taken at 12 and 24 months of age. DESIGN: Home videotapes of 56 children's first and second birthday parties were collected from parents of young children with ASD with and without a reported history of regression and typically developing children. Child behaviors were coded by raters blind to child diagnosis and regression history. A parent interview that elicited information about parents' recall of early symptoms from birth was also administered. SETTING: Participants were recruited from a multidisciplinary study of autism conducted at a major university. PARTICIPANTS: Fifteen children with ASD with a history of regression, 21 children with ASD with early-onset autism, and 20 typically developing children and their parents participated. MAIN OUTCOME MEASURES: Observations of children's communicative, social, affective, repetitive behaviors, and toy play coded from videotapes of the toddlers' first and second birthday parties. RESULTS: Analyses revealed that infants with ASD with regression show similar use of joint attention and more frequent use of words and babble compared with typical infants at 12 months of age. In contrast, infants with ASD with early onset of symptoms and no regression displayed fewer joint attention and communicative behaviors at 12 months of age. By 24 months of age, both groups of toddlers with ASD displayed fewer instances of word use, vocalizations, declarative pointing, social gaze, and orienting to name as compared with typically developing 24-month-olds. Parent interview data suggested that some children with regression displayed difficulties in regulatory behavior before the regression occurred. CONCLUSION: This study validates the existence of early autistic regression.

Age of Onset↗

PubMed2005

Individuals with autism spectrum disorder show normal responses to a fear potential startle paradigm.

The present study utilized a fear potentiated startle paradigm to examine amygdala function in individuals with autism spectrum disorder. Two competing hypotheses regarding amygdala dysfunction in autism have been proposed: (1) The amygdala is under-responsive, in which case it would be predicted that, in a fear potentiated startle experiment, individuals with autism would exhibit decreased fear conditioning and/or potentiation, and (2) The amygdala is over responsive, in which case an exaggerated potentiation of the startle response would be predicted. Fourteen adolescents and adults diagnosed with autism spectrum disorder and 14 age, gender, IQ, and anxiety level-matched typical adolescents and adults participated. Both participants with autism and typical participants potentiated the startle response following fear conditioning and no group differences in the latency or amplitude of the potentiated startle response were found. These results suggest that this aspect of amygdala function, namely fear conditioning and potentiation of the startle response, is intact in individuals with autism.

Adolescent↗

PubMed2005

Challenges in evaluating psychosocial interventions for Autistic Spectrum Disorders.

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

Autistic Disorder↗

PubMed2005

Variation in early developmental course in autism and its relation with behavioral outcome at 3-4 years of age.

The aims of the present study were to describe variations in the early course of development in autism by utilizing an in-depth parent interview that incorporated techniques to improve accuracy of parent recall, and to examine the relation between variations in early developmental course in autism and behavioral outcome at 3-4 years of age. The Early Development Interview, which consisted of questions about child's behavior in several domains from birth through 2 years of age, was created and administered to parents of 72 3-4-year-old children with autism spectrum disorder and 34 3-4-year-old children with developmental delay, who were matched on mental and chronological age, and 39 1-4-year-old typically developing children, who were matched to the clinical groups on mental age. At 3-4 years of age, children were administered standardized measures (some clinician administered and some parent report); these included verbal and nonverbal IQ, autism symptom severity, and adaptive and aberrant behavior. Based on the Early Development Interview, children with autism spectrum disorder (ASD) were reported to have elevated symptoms in the social and regulatory domains by 3-6 months. By 12-15 months, parents of children with ASD reported significantly higher levels of social symptoms than parents of children with developmental delay. At 3-4 years of age, children with autism with early vs. late onset of symptoms, and with vs. without a history of loss of skills (regression) were not found to differ on standardized tests of verbal and nonverbal IQ and observational measures of autism symptom severity.

Age Factors↗

PubMed2005

Neurocognitive and electrophysiological evidence of altered face processing in parents of children with autism: implications for a model of abnormal development of social brain circuitry in autism.

Neuroimaging and behavioral studies have shown that children and adults with autism have impaired face recognition. Individuals with autism also exhibit atypical event-related brain potentials to faces, characterized by a failure to show a negative component (N170) latency advantage to face compared to nonface stimuli and a bilateral, rather than right lateralized, pattern of N170 distribution. In this report, performance by 143 parents of children with autism on standardized verbal, visual-spatial, and face recognition tasks was examined. It was found that parents of children with autism exhibited a significant decrement in face recognition ability relative to their verbal and visual spatial abilities. Event-related brain potentials to face and nonface stimuli were examined in 21 parents of children with autism and 21 control adults. Parents of children with autism showed an atypical event-related potential response to faces, which mirrored the pattern shown by children and adults with autism. These results raise the possibility that face processing might be a functional trait marker of genetic susceptibility to autism. Discussion focuses on hypotheses regarding the neurodevelopmental and genetic basis of altered face processing in autism. A general model of the normal emergence of social brain circuitry in the first year of life is proposed, followed by a discussion of how the trajectory of normal development of social brain circuitry, including cortical specialization for face processing, is altered in individuals with autism. The hypothesis that genetic-mediated dysfunction of the dopamine reward system, especially its functioning in social contexts, might account for altered face processing in individuals with autism and their relatives is discussed.

Autistic Disorder↗