Individuals with autism spectrum disorder (ASD) exhibit early and lifelong abnormalities in adaptive allocation of visual attention. Previous studies have shown white matter compromise in children and adults with ASD, which may relate to impaired function in distributed networks.
Objectives:
The goals of the present study were to 1) investigate whether white matter integrity in regions-of-interest (ROIs) associated with attention networks differ between children with ASD and typically developing (TD) children, and 2) to examine the relationship between attention network efficiency and white matter integrity in ASD and TD children.
Methods:
Diffusion tensor imaging (DTI) data of 17 children with ASD and 14 TD children were acquired from a 3T MRI scanner. Six ROIs were placed on white matter tracts based on previous literature associating these areas with attention. These ROIs were derived from Johns Hopkins University atlas for uncinate fasciculus, inferior longitudinal fasciculus, genu of the corpus callosum, anterior corona radiata, cingulum bundle, and superior longitudinal fasciculus. Fractional anisotropy (FA) was calculated for each ROI and was averaged over all ROIs for a global measure of white matter integrity of attentional networks. Participants also completed three 96-trial blocks of the Attention Network Test. Alerting, orienting, and executive attention network scores for each participant were calculated.
Results:
FA of white matter associated with the attentional networks was significantly reduced in the ASD group compared to the TD group (0.32 ± 0.04 for ASD versus 0.35 ± 0.02 for TD (p=0.04)). FA was positively correlated with orienting scores in the TD group (r=0.51, p=0.05); however, this correlation was absent in the ASD group (r=0.11, p=0.67).
Conclusions:
Our findings suggest that white matter compromise may contribute to attentional inefficiency in ASD. Absence of typical relationships between integrity of crucial white matter tracts and attention scores may indicate atypical network organization for attention. This was specifically observed for orienting, which was also found to be the attentional network of primary impairment in ASD in a behavioral study (Keehn et al., J Child Psychol Psychiatry, 2010).