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Friday, May 8, 2009
Northwest Hall (Chicago Hilton)
3:30 PM
Background: A disturbance in the ability to rapidly shift attention between auditory and visual modalities has been observed among individuals with known cerebellar damage and individuals with autism (AD). Based on the strong influence that genetics play in the presence of autism and the spectrum of abnormalities that first-degree relatives of individuals with autism show, it is possible that siblings of children with autism would also show structural changes in the brain, including the cerebellum, causing deficits in the ability to rapidly shift attention, but possibly to a lesser degree than the autistic proband.,
Objectives: The purpose of this study is to determine if siblings of individuals with autism also show this deficit in shifting attention, which could indicate that shifting attention could be an endophynotypic marker hey exhibit a phenotypic similarity to their sibling with autism and shift attention deficits are part of the broad autistic phenotype.
Methods: Participants included 20 individuals who have a first-degree sibling with a diagnosis of AD (SIB group) and 19 individuals with no known medical or psychiatric disorders who do not have any siblings with autism or other Pervasive Developmental Disorder (NC group).Individuals participated in two types of attentional tasks: focus attention and shifting attention. Five time bins, which indicate the length of time between the presentation of the cue and the target stimuli, were used to categorize responses. The time bins were as follows: 1) 0.4-2.49 seconds; 2) 2.5-4.49 seconds; 3) 4.5-6.49 seconds; 4) 6.5-10.49 seconds; and 5) 10.5 to greater than 30 seconds. There were two conditions, both of which required the participant to press a button on the joystick in response to a rare target. The two conditions included focus attention and shift attention. Within these two conditions there were two modalities- visual and auditory. In all conditions the participants were required to selectively attend to the designated stimulus modality, discriminate between targets and exhibit a simple motor response (button press) to the detected targets.
Results: The between subjects comparison (omnibus F) was non-significant, suggesting siblings of children with autism performed comparably to normal control subjects on the shifting attention tasks and there were no between-group differences. A planned comparison was performed, examining the response accuracy for the two groups (SIB and NC) in the shortest time bin of the shifting tasks. There was not a statistically significant difference between groups on either the visual shifting task (F(1, 37) = 0.045; p = 0.834) or the auditory shifting task (F(1, 37) = 0.126; p = 0.724). Interestingly, post-hoc analyses did suggest that males may demonstrate a shifting attention deficit. Cases were split into male and female. For the visual and auditory shifting tasks amongst the males only, p-values approached significance. These comparisons showed moderate effect sizes (Eta2=0.22 and 0.25). This would have to be further assessed with a sample including more male participants.
Conclusions: Overall, results suggest that typically developing male sibilings of AD probands may show evidence of an endophyotype involving a reduced capacity to perform inter-modality rapid shifting of attention.
Objectives: The purpose of this study is to determine if siblings of individuals with autism also show this deficit in shifting attention, which could indicate that shifting attention could be an endophynotypic marker hey exhibit a phenotypic similarity to their sibling with autism and shift attention deficits are part of the broad autistic phenotype.
Methods: Participants included 20 individuals who have a first-degree sibling with a diagnosis of AD (SIB group) and 19 individuals with no known medical or psychiatric disorders who do not have any siblings with autism or other Pervasive Developmental Disorder (NC group).Individuals participated in two types of attentional tasks: focus attention and shifting attention. Five time bins, which indicate the length of time between the presentation of the cue and the target stimuli, were used to categorize responses. The time bins were as follows: 1) 0.4-2.49 seconds; 2) 2.5-4.49 seconds; 3) 4.5-6.49 seconds; 4) 6.5-10.49 seconds; and 5) 10.5 to greater than 30 seconds. There were two conditions, both of which required the participant to press a button on the joystick in response to a rare target. The two conditions included focus attention and shift attention. Within these two conditions there were two modalities- visual and auditory. In all conditions the participants were required to selectively attend to the designated stimulus modality, discriminate between targets and exhibit a simple motor response (button press) to the detected targets.
Results: The between subjects comparison (omnibus F) was non-significant, suggesting siblings of children with autism performed comparably to normal control subjects on the shifting attention tasks and there were no between-group differences. A planned comparison was performed, examining the response accuracy for the two groups (SIB and NC) in the shortest time bin of the shifting tasks. There was not a statistically significant difference between groups on either the visual shifting task (F(1, 37) = 0.045; p = 0.834) or the auditory shifting task (F(1, 37) = 0.126; p = 0.724). Interestingly, post-hoc analyses did suggest that males may demonstrate a shifting attention deficit. Cases were split into male and female. For the visual and auditory shifting tasks amongst the males only, p-values approached significance. These comparisons showed moderate effect sizes (Eta2=0.22 and 0.25). This would have to be further assessed with a sample including more male participants.
Conclusions: Overall, results suggest that typically developing male sibilings of AD probands may show evidence of an endophyotype involving a reduced capacity to perform inter-modality rapid shifting of attention.