Atypical Visual Attention in Infants at High Genetic Risk for Autism Spectrum Disorder

Background: Evidence indicates that developmental changes in visual attention between 6 to 12 months-of-age predict later autism spectrum diagnoses (ASD; Ibanez et al., 2008). Infants with fragile X syndrome (FXS) are at high risk for developing ASD, as are infants with an older sibling diagnosed with ASD (ASIBs). Abnormal attention to objects have been documented as early as two months of age and extending into preschool years in ASIBs (Jones & Klin, 2013). Similar findings have been identified in FXS (Roberts et al., 2012). To date, no groups have investigated how these two high-risk groups differ in their attention to objects. Investigating early deficits in visual attention in infants at high risk for ASD can refine the infant phenotype of FXS and ASIBs and serve as a potential prognostic indicator of ASD risk.

Objectives: Our aim was a cross-syndrome characterization of the relationship of object attention in high risk samples at 9, 12 and 24 months of age and its predictive value to ASD severity at 24 months.

Methods: Participants included infant males with FXS (n=18), ASIBs (n=26), and typically developing infants (TD; n=28) assessed at 9, 12 and 24 months of age. Proportion of time looking at toy keys was the dependent variable (LabTAB; Goldsmith & Rothbart, 1996) with visual attention coded offline (κ=0.85). The Mullen controlled for developmental level, and the Autism Diagnostic Observation Schedule-2 reflected autism severity at the 24-month outcome.

Results: Developmental level was included in all models. ANCOVAs suggest no groups differences at 9 or 12 months of age (ps>0.05) in attention to objects. However, at 24 months of age there were group differences (F(2,54)=3.09, p=0.05, partial η²= 0.10). TD infants spent more time looking at the object in comparison to ASIBs. Regression models examined object attention predicting later ASD severity. At 9 months, increased object attention was predicative of decreased ASD severity at 24 months in ASIBs (B=-11.43, SE=2.96, p=0.01), but not in FXS (B=-11.66, SE=5.84, p=0.11). At 12 months, increased object attention was associated with increased ASD severity at 24 months in infants with FXS (B=20.46, SE=8.96, p=0.04), but not in ASIBs (B=-5.11, SE=4.23, p=0.25). At 24 months, object attention was not predictive of ASD severity at 24 months in FXS (B=2.75, SE=3.86, p=0.49) or ASIBs (B=5.42, SE=3.02, p=0.09).

Conclusions: Our results suggest infants with FXS, ASIBs, and TD infants display similar profiles in their attention to objects during the first two years of life, with differences emerging at 24 months of age between infant ASIBs and TD infants. Object attention appears to be related to ASD outcomes differentially in these two high-risk groups. Decreased object attention in ASIBs at 9 months was associated with increased ASD symptoms, whereas increased object attention at 12 months in FXS was related to increased ASD symptoms. These findings suggest that, although object attention may manifest differently in these two groups, they both are associated with ASD outcomes. It appears different mechanisms specific to these two phenotypes impacting object attention may produce similar outcomes relative to ASD.