International Meeting for Autism Research (London, May 15-17, 2008): Impaired Disengagement and its Relationship to Temperament in Infants at High Risk for ASD
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Impaired Disengagement and its Relationship to Temperament in Infants at High Risk for ASD

Saturday, May 17, 2008: 11:30 AM
Bourgogne (Novotel London West)
S. E. Bryson , Pediatrics and Psychology, Dalhousie University/IWK Health Centre, Halifax, NS, Canada
N. Garon , Autism Research Centre, IWK Health Centre, Halifax, NS, Canada
J. Brian , Autism Research Unit, and Bloorview Research Institute, Hospital for Sick Children & Bloorview Kids Rehab, Toronto, ON, Canada
I. M. Smith , Dalhousie University, Halifax, NS, Canada
T. McCormick , Autism Research Centre, IWK Health Centre, Halifax, NS, Canada
W. Roberts , Department of Pediatrics, Hospital for Sick Children & Bloorview Kids Rehab, University of Toronto, Toronto, ON, Canada
P. Szatmari , Offord Centre for Child Studies, McMaster University, Hamilton, ON, Canada
L. Zwaigenbaum , Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
Background: Young children with ASD have difficulty disengaging visual attention from one of two competing stimuli (Landry & Bryson, 2004), but little is known about the early emergence or underlying mechanisms of this impairment.  

Objectives: To determine whether impaired disengagement distinguishes ASD in high-risk infants, and whether this impairment is associated with the Behavioural Approach dimension of temperament (Rothbart & Bates, 1998).

Methods: Participants were recruited from our prospective study of high-risk infants with an older sibling with ASD, and low-risk controls with no family history of ASD. Infants were assessed on a visual orienting paradigm at 6 and 12 months of age, and their parents completed the Infant Behavor Quesionnaire at 12 months. An independent diagnositc assessment for ASD was conducted at 36 months of age, yielding 3 groups: ASD sibs (n=14), non-ASD sibs (n=43) and controls (n=44).

Results: A repeated measures ANOVA conducted on reaction times (RTs) to disengage and shift attention revealed a significant Group X Attention Condition X Side interaction, F(2, 98)=3.77, p<.03. At 12 (vs. 6) months, infants who were subsequently diagnosed with ASD were distinguished from non-ASD sibs and controls by significantly longer disengage RTs on the left than on the right side of space. No significant left-right RT differences were found for either the non-ASD sibs or controls. Left-right asymmetries in disengaging visual attention were significantly related to low Behavioural Approach in both the ASD sibs (r=.49, p=.06) and non-ASD sibs (r=.41, p=.003).  

Conclusions: Our finding that asymmetries in disengaging attention distinguish ASD at 12 but not 6 months implicates dysfunction of frontal or executive control of attention (Johnson, 1996). This asymmetry, and its relationship to low Behavioural Approach, is consistent with evidence of right cortical asymmetry in a subgroup with ASD (Mundly et al., 2007; Sutton et al., 2005).

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