Non-right-handedness in children born extremely preterm: Relation to early neuroimaging and long-term neurodevelopment

Abstract

Objective This study aimed to define the prevalence and predictors of non-right-handedness and its link to long-term neurodevelopmental outcome and early neuroimaging in a cohort of children born extremely preterm (<28 weeks gestation). Methods 179 children born extremely preterm admitted to the Neonatal Intensive Care Unit of our tertiary centre from 2006–2013 were included in a prospective longitudinal cohort study. Collected data included perinatal data, demographic characteristics, neurodevelopmental outcome measured by the Bayley Scales of Infant and Toddler Development at 2 years and the Movement Assessment Battery for Children at 5 years, and handedness measured at school age (4–8 years). Magnetic resonance imaging performed at term-equivalent age was used to study overt brain injury. Diffusion tensor imaging scans were analysed using tract-based spatial statistics to assess white matter microstructure in relation to handedness and neurodevelopmental outcome. Results The prevalence of non-right-handedness in our cohort was 22.9%, compared to 12% in the general population. Weaker fine motor skills at 2 years and paternal non-right-handedness were significantly associated with non-right-handedness. Both overt brain injury and fractional anisotropy of white matter structures on diffusion tensor images were not related to handedness. Fractional anisotropy measurements showed significant associations with neurodevelopmental outcome. Conclusions Our data show that non-right-handedness in children born extremely preterm occurs almost twice as frequently as in the general population. In the studied population, non-right-handedness is associated with weaker fine motor skills and paternal non-right-handedness, but not with overt brain injury or microstructural brain development on early magnetic resonance imaging.

Is Handedness at Five Associated with Prenatal Factors?

“…Even though we did not find a two-fold increase of the percentage of non-right-handers in preterm compared to full-term children, as shown in Domellöf et al’s meta-analysis [ 48 ], the significantly lower absHI in children born after less than 37 weeks as compared to full-term children goes in that direction. This is in line with a recent study showing a large percentage of non-right-handers in 4–8 year olds formerly extremely preterm [ 77 ]. If one considers that the last weeks of pregnancy are important for reinforcing a tendency toward right-handedness [ 2 ], then one could expect that lacking the last weeks of pregnancy could result in a lower absHI.…”

“…In the literature, when a difference between the effect of father’s and the mother’s handedness was found, it was frequently the mother’s handedness which was more important [ 73 , 74 , 75 , 76 ]. However, our results fit with other studies showing that, among non-right handed children, there are more left-handed fathers, but no more left-handed mothers, than among right-handed children [ 44 , 77 ], both sets of results concerning extremely preterm children. If more data confirm the specific effect of the father’s handedness on the child’s own hand preference, the question will remain to understand the genetic, or pre or postnatal environmental mechanisms which could explain it.…”

Shape variability of the central sulcus in the developing brain: a longitudinal descriptive and predictive study in preterm infants

“…Nevertheless, it has been reported that additive genetic effects only accounts for a quarter of the variance in handedness (Medland et al, 2009), therefore this left-hander-selection-choice is somewhat arbitrary. However, recent studies reported that paternal non-right-handedness was significantly related to left-hand preference in children (van Heerwaarde et al, 2020;Fagard et al, 2021). In our study, all the selected left-handers appeared to have a left-handed father, comforting our criteria choice.…”

“…We dichotomized the children group according to their poor and good fine motor outcome, removing children with borderline results from the classification. For the mABC total score, a score inferior or equal to the 5 th percentile indicates definite motor problems; between the 6 th and 15 th percentiles indicates borderline performance; and strictly above the 15 th percentile indicates normal motor development (van Heerwaarde et al, 2020). Since for the manual dexterity subscore no percentile cut-offs have been assessed, we used the same cut-offs in our study population, with the corresponding standard scores for each percentile range: children whose standard score ranked between 1 and 5 were assigned to the poor fine motor outcome group (n=15), children who ranked strictly above 7 were assigned to the good fine motor outcome group (n=35), and children ranking 6 or 7 (n=16) were considered as borderline and were not included in the classification analyses.…”

Development of laterality: Asymmetrical human behaviors and perceptual biases

“…However, another recent study failed to find an association between brain injury and atypical handedness (van Heerwaarde et al, 2020). While it may be due to low statistical power as the authors suggested, these results indicate that handedness has different origins, resulting from genetic and environmental pathological factors (van Heerwaarde et al, 2020).…”