Helen Tager-Flusberg

CaV1.2 Calcium Channel Dysfunction Causes a Multisystem Disorder Including Arrhythmia and Autism

Ca(V)1.2, the cardiac L-type calcium channel, is important for excitation and contraction of the heart. Its role in other tissues is unclear. Here we present Timothy syndrome, a novel disorder characterized by multiorgan dysfunction including lethal arrhythmias, webbing of fingers and toes, congenital heart disease, immune deficiency, intermittent hypoglycemia, cognitive abnormalities, and autism. In every case, Timothy syndrome results from the identical, de novo Ca(V)1.2 missense mutation G406R. Ca(V)1.2 is expressed in all affected tissues. Functional expression reveals that G406R produces maintained inward Ca(2+) currents by causing nearly complete loss of voltage-dependent channel inactivation. This likely induces intracellular Ca(2+) overload in multiple cell types. In the heart, prolonged Ca(2+) current delays cardiomyocyte repolarization and increases risk of arrhythmia, the ultimate cause of death in this disorder. These discoveries establish the importance of Ca(V)1.2 in human physiology and development and implicate Ca(2+) signaling in autism.

An Investigation of Language Impairment in Autism: Implications for Genetic Subgroups.

Autism involves primary impairments in both language and communication, yet in recent years the main focus of research has been on the communicative deficits that define the population. The study reported in this paper investigated language functioning in a group of 89 children diagnosed with autism using the ADI–R, and meeting DSM–IV criteria. The children, who were between 4 and 14 years old, were administered a battery of standardised language tests tapping phonological, lexical, and higher-order language abilities. The main findings were that among the children with autism there was significant heterogeneity in their language skills, although across all the children, articulation skills were spared. Different subgroups of children with autism were identified on the basis of their performance on the language measures. Some children with autism have normal language skills; for other children, their language skills are significantly below age expectations. The profile of performance across the standardised measures for the languageimpaired children with autism was similar to the profile that defines the disorder specific language impairment (or SLI). The implications of this language impaired subgroup in autism for understanding the genetics and definition of both autism and SLI are discussed.

A componential view of theory of mind: evidence from Williams syndrome.

In this paper we argue that there are two distinct components of a theory of mind: a social-cognitive and a social-perceptual component. Evidence for this proposal is presented from various sources, including studies of children with Williams syndrome, a rare genetic neurodevelopmental disorder. Earlier work has demonstrated that people with Williams syndrome appear to be spared in the social-perceptual component of a theory of mind. In this paper we present evidence that they are not spared in the social-cognitive component of theory of mind. Three experiments with young children with Williams syndrome were conducted. In each experiment the children with Williams syndrome were compared to age-, IQ-, and language-matched children with Prader-Willi syndrome, and children with non-specific mental retardation. The experiments used different measures of theory of mind ability, including false belief (Experiment 1), explanation of action (Experiment 2), and recognition of emotional expressions (Experiment 3). In none of these experiments did the children with Williams syndrome evidence superior performance compared to the control groups. The results from this and other studies on Williams syndrome support the view that the social-cognitive and social-perceptual components of a theory of mind are dissociable. In Williams syndrome only the latter components, which are linked to distinct neurobiological substrates, are spared.

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.

On the nature of linguistic functioning in early infantile autism

This paper provides a review of studies conducted on linguistic functioning in autistic children, within the framework developed in normal language acquisition research. Despite certain methodological weaknesses, the research consistently shows that phonological and syntactic development follow the same course as in normal children and in other disordered groups, though at a slowed rate, while semantic and pragmatic functioning may be specially deficient in autism. These findings are related to other recent studies on the relative independence of different aspects of language.

Activation of the fusiform gyrus when individuals with autism spectrum disorder view faces

Prior imaging studies have failed to show activation of the fusiform gyrus in response to emotionally neutral faces in individuals with autism spectrum disorder (ASD) [Critchley et al., Brain 124 (2001) 2059; Schultz et al., Arch. Gen. Psychiatry 57 (2000) 331]. However, individuals with ASD do not typically exhibit the striking behavioral deficits that might be expected to result from fusiform gyrus damage, such as those seen in prosopagnosia, and their deficits appear to extend well beyond face identification to include a wide range of impairments in social perceptual processing. In this study, our goal was to further assess the question of whether individuals with ASD have abnormal fusiform gyrus activation to faces. We used high-field (3 T) functional magnetic resonance imaging to study face perception in 11 adult individuals with autism spectrum disorder (ASD) and 10 normal controls. We used face stimuli, object stimuli, and sensory control stimuli (Fourier scrambled versions of the face and object stimuli) containing a fixation point in the center to ensure that participants were looking at and attending to the images as they were presented. We found that individuals with ASD activated the fusiform face area and other brain areas normally involved in face processing when they viewed faces as compared to non-face stimuli. These data indicate that the face-processing deficits encountered in ASD are not due to a simple dysfunction of the fusiform area, but to more complex anomalies in the distributed network of brain areas involved in social perception and cognition.

A replication of the Autism Diagnostic Observation Schedule (ADOS) revised algorithms

OBJECTIVE To replicate the factor structure and predictive validity of revised Autism Diagnostic Observation Schedule algorithms in an independent dataset (N = 1,282). METHOD Algorithm revisions were replicated using data from children ages 18 months to 16 years collected at 11 North American sites participating in the Collaborative Programs for Excellence in Autism and the Studies to Advance Autism Research and Treatment. RESULTS Sensitivities and specificities approximated or exceeded those of the old algorithms except for young children with phrase speech and a clinical diagnosis of pervasive developmental disorders not otherwise specified. CONCLUSIONS Revised algorithms increase comparability between modules and improve the predictive validity of the Autism Diagnostic Observation Schedule for autism cases compared to the original algorithms.

Clinical Assessment and Management of Toddlers With Suspected Autism Spectrum Disorder: Insights From Studies of High-Risk Infants

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.

The influence of language on theory of mind: a training study

This study investigated the role of language in the development of theory of mind. It was hypothesized that the acquisition of the syntactic and semantic properties of sentential complements would facilitate the development of a representational theory of mind. Sixty preschoolers who failed false belief and sentential complement pretests were randomly assigned to training on false belief, sentential complements, or relative clauses (as a control group). All the children were post-tested on a set of different theory of mind tasks, sentential complements and relative clauses. The main findings were that the group trained on sentential complements not only acquired the linguistic knowledge fostered by the training, but also significantly increased their scores on a range of theory of mind tasks. In contrast, false belief training only led to improved theory of mind scores but had no influence on language. The control group, trained on relative clauses, showed no improvement on theory of mind posttests. These findings are taken as evidence that the acquisition of sentential complements contributes to the development of theory of mind in preschoolers.

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.