Early visual attention in preterm and fullterm infants in relation to cognitive and motor outcomes at school age: an exploratory study

Abstract

Objective: Preterm infants are exposed to the visual environment earlier than fullterm infants, but whether early exposure affects later development is unclear. Our aim was to investigate whether the development of visual disengagement capacity during the first 6 months postterm was associated with cognitive and motor outcomes at school age, and whether associations differed between fullterms and low-risk preterms.

Method: Seventeen fullterms and ten low-risk preterms were tested in a gaze shifting task every 4 weeks until 6 months postterm. The longitudinal data were converted into single continuous variables by fitting the data with an S-shaped curve (frequencies of looks) or an inverse model (latencies of looks). Neuropsychological test results at school age were converted into composite z scores. We then performed linear regression analyses for each functional domain at school age with the variables measuring infant visual attention as separate predictors and adjusting for maternal level of education and group (fullterms versus preterms). We included an interaction term, visual attention*group, to determine whether predictive relations differed between fullterms and preterms.

Results: A slower development of disengagement predicted poorer performance on attention, motor skills, and handwriting, irrespective of fullterm or preterm birth. Predictive relationships differed marginally between fullterms and preterms for inhibitory attentional control (P = 0.054) and comprehensive reading (P = 0.064).

Conclusion: This exploratory study yielded no indications of a clear advantage or disadvantage of the extra visual exposure in healthy preterm infants. We tentatively conclude that additional visual exposure does not interfere with the ongoing development of neuronal networks during this vulnerable period of brain development.

Keywords: cognition; frequency of looks; functional development; longitudinal study; low-risk preterm infants; motor skills; response latencies; visual competing stimuli.

Figure 1

Composite scores on cognitive and motor outcomes, expressed as z scores, in fullterm-born (dotted) and preterm-born children (hatched). Data are presented as box and whisker plots. The boxes represent values between the 25th and 75th percentiles. The whiskers represent the range of the values, with the exception of outliers, which are represented as circles. Statistical differences were calculated after controlling for maternal education. IQ, intelligence quotient; EF, executive functioning **P < 0.05; *P < 0.1.

Figure 2

Age in weeks at which the infant reached a relative frequency of looks of 50% (50%-looks) under the non-competitive condition in fullterm-born (dotted) and preterm-born children (hatched) with normal (Levels I–III) and abnormal (Levels IV–V) scores on the Cito comprehensive reading test. The data in the graphs are presented as box and whisker plots. Boxes represent the individual values between the 25th and 75th centiles (interquartile range); whiskers represent the range of the values, with the exception of outliers. The outliers are represented by the circles and defined as values between 1.5 interquartile range and 3 interquartile ranges from the end of a box.

Figure 3

The speed at which the infant grows toward a lower reaction time (b1) in relation to z scores on TEA-Ch-NL opposite world (inhibition). A higher b1 value represents a slower development toward the adult level reaction time (200 ms).