Autism: definition, neurobiology, screening, diagnosis.

Autism (ie, the autism spectrum disorders) is now recognized in 1 in 150 children. This article highlights the definition, neurobiology, screening, and diagnosis of autism. The genetics, immunology, imaging, and neurophysiology of autism are reviewed, with particular emphasis on areas that impact pediatricians. Early recognition of the social deficits that characterize autism is key to maximizing the potential of these children.

Deconstructing autism spectrum disorders: clinical perspective.

Autism spectrum disorder (ASD) is a term used to describe a heterogeneous group of children whose behaviorally defined characteristics overlap with the clinical manifestations of a variety of distinct behaviorally defined developmental disorders. ASD has many etiologies and strong but complex genetic and molecular underpinnings supporting genetic and phenotypic heterogeneity. Clinical and biological heterogeneity in ASD is consistent with the view of autism spectrum disorders as the expression of atypical brain development resulting in variable clinical manifestations that reflect differences in specific genetic and molecular pathways. It is likely that there are risk genes and early environmental risk factors for ASD that contribute to an altered trajectory of brain and behavioral development. These alterations are hypothesized to lead to altered social interaction and consequently to abnormal development of the neural networks critical for social and communicative interaction. This amplifies the abnormal socio-communicative developmental process leading to the full ASD syndrome. The hope is that interventions can alter these early developmental processes and put an infant back on a more typical developmental trajectory. In this discussion an overview of the limitations of the triad of behaviors used to diagnose ASD, specifically from the perspective of how these issues impact diagnosis and treatment of children with ASD will be presented and the clinical boundaries of the autism spectrum will be explored.

Exploring the relationship between autism spectrum disorder and epilepsy using latent class cluster analysis.

Epilepsy co-occurs frequently in autism spectrum disorders (ASD). Understanding this co-occurrence requires a better understanding of the ASD-epilepsy phenotype (or phenotypes). To address this, we conducted latent class cluster analysis (LCCA) on an ASD dataset (N = 577) which included 64 individuals with epilepsy. We identified a 5-cluster solution with one cluster showing a high rate of epilepsy (29%), earlier age at first recognition, and high rates of repetitive object use and unusual sensory interests. We also conducted LCCA on an ASD-epilepsy subset from the overall dataset (N = 64) which yielded three clusters, the largest of which had impairments in language and motor development; the remaining clusters, while not as developmentally impaired were characterized by different levels of repetitive and sensory behaviors.

What is new in autism?

PURPOSE OF REVIEW: Autism is now recognized in one out of 150 children. This review highlights the topics within the growing autism literature that are shaping current thinking on autism and advancing research and clinical understanding of autism spectrum disorders. RECENT FINDINGS: The role of single-stranded microdeletions and epigenetic influences on brain development has dramatically altered our understanding of the etiology of the autisms. Recent research has focused on the role of synapse structure and function as central to the development of autism and suggests possible targets of interventions. Brain underconnectivity has been a focus in recent imaging studies and has become a central theme in conceptualizing autism. Despite increased awareness of autism there is no 'epidemic' and no one cause for autism. Data from the sibling studies are identifying early markers of autism and defining the broader autism phenotype. SUMMARY: Larger datasets in genetics, a focus on the early signs of autism, and increased recognition of the importance of defining subgroups of children with autism are leading to a greater understanding of the etiologies of autism. A growing interest in defining the molecular biology of social cognition, which is at the core of autism, will lead to expansion of our presently limited choices of mechanistically based interventions.

Language regression in childhood.

Language regression is observed both in autistic regression and as part of acquired epileptic aphasia (Landau-Kleffner Syndrome). We prospectively identified 177 children with language regression at four major medical centers, and their clinical characteristics were recorded. Their mean age at regression was 22.8 months. The mean time-to-specialist referral was 38 months of age. Most children (88%) met criteria for autism or manifested autistic features. Males (P = 0.02) and children less than 3 years of age who regressed (P = 0.016) had a higher probability of developing autistic behaviors. Seizures were more common in children who regressed after they reached 3 years of age (P < 0.001), and children with seizures were less likely to have associated autistic regression (P < 0.001). Electroencephalogram abnormalities were reported in 37% of patients and were more common in children with seizures (P < 0.001). At last follow-up, language function was impaired in 88% of the children, although some improvement was noted in 57%. We conclude that the loss of previously acquired language at any age, even if that language only includes a few words or communicative gestures, is often associated with a more global regression in cognition and/or behavior and has serious implications for future function. Early identification and referral of these children is necessary to allow for diagnosis and intervention.