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Autism neuropsychological theory: A review (in press)

Wed, 1 Dec 2010 18:40:51 -0500

Abstract

This chapter reviews the major neuropsychological theories of ASD from the last several decades, which we have sorted into the following categories: executive functioning, information processing, social motivation, and social cognition. We close with a section on emerging topics, relatively recent theories and models for which researchers are building empirical support, such as mirror neurons and their relevance to mimicry and imitation, animal models, and neural networks. Some of the theories discussed here are dealt with in more detail in specific chapters in this volume.

Mother-infant interaction and nonverbal communication in infants at risk for autism

Tue, 22 Jun 2010 15:19:24 -0400

Abstract

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.

Response to distress in infants at risk for autism

Tue, 8 Jun 2010 18:10:36 -0400

Abstract

Background: Infants and preschoolers with ASD show impairment in their responses to other people's distress relative to children with other developmental delays and typically developing children. This deficit is expected to disrupt social interactions, social learning, and the formation of close relationships. Response to distress has not been evaluated previously in infants with ASD earlier than 18 months of age.

Methods: Participants were 103 infant siblings of children with autism and 55 low-risk controls. All children were screened for ASD at 36 months and 14 were diagnosed with ASD. Infants' responsiveness to distress was evaluated at 12, 18, 24, and 36 months. An examiner pretended to hit her finger with a toy mallet and infants' responses were video-recorded. Attention to the examiner and congruent changes in affect were coded on four-point Likert scales.

Results: Cross-sectional and longitudinal analyses confirm that the ASD group paid less attention and demonstrated less change in affect in response to the examiner's distress relative to the high-risk and low-risk participants who were not subsequently diagnosed with ASD. Group differences remained when verbal skills and general social responsiveness were included in the analytic models.

Conclusions: Diagnostic groups differ on distress response from 12 to 36 months of age. Distress-response measures are predictive of later ASD diagnosis above and beyond verbal impairments. Distress response is a worthwhile target for early intervention programs.

Emergence of early behavioral signs of autism

Mon, 8 Feb 2010 18:29:13 -0500

Abstract

Objective: 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.

Method: 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.

Results: 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.

Conclusions: 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.

Play in autism siblings

Fri, 29 Jan 2010 18:23:42 -0500

Abstract

We observed infant siblings of children with autism later diagnosed with ASD (ASD siblings; n = 17), infant siblings of children with autism with and without other delays (Other Delays and No Delays siblings; n = 12 and n = 19, respectively) and typically developing controls (TD controls; n = 19) during a free-play task at 18 months of age. Functional, symbolic, and repeated play actions were coded. ASD siblings showed fewer functional and more non-functional repeated play behaviors than TD controls. Other Delays and No Delays siblings showed more non-functional repeated play than TD controls. Group differences disappeared with the inclusion of verbal mental age. Play as an early indicator of autism and its relationship to the broader autism phenotype is discussed.