Genetic and environmental contributions to individual differences in visual attention and oculomotor control in early infancy

Abstract

Oculomotor abilities and basic visual attention have been proposed as potential endophenotypes for neurodevelopmental conditions including autism spectrum disorder (ASD). Here, using a unique infant twin approach we assessed the role of genes and environments for eye movement latencies and visual attention disengagement (disengagement), and the link between these phenotypes and ASD predisposition and traits. A total of 450 twins (225 pairs, 57% Monozygotic) aged 5-6 months were included in the study (Babytwins Study Sweden). The twins eye movements were monitored with eye-tracking technology while performing the gap-overlap task at 5 months, , and were assessed for autistic traits using a parent-reported measure at 36 months . Results showed expected experimental effects, including a slowing down of latencies to appearing peripheral targets in the context of an on-screen competing stimulus (“disengagement cost"). All included phenotypes were influenced by genetic factors (h2=40-60%) and unique environment (e2=40-60%), whereas the contribution of shared environment was negligible. A moderate-to-high fraction (39-91%) of etiological influences were shared between conditions and explained by a highly heritable (h2=0.613) latent factor likely representing basic oculomotor control; nonetheless, disengagement cost was associated with unique genetic factors. Disengagement was not associated with later ASD traits nor with ASD-linked common genetic variants. These results reveal the genetic underpinnings to variability in basic oculomotor and attentional functions in early infancy, and suggest that visual attention functions are etiologically separable from basic oculomotor control. Disengagement in early infancy was not associated with genetic predisposition to ASD or later ASD traits in the general population.