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INTRODUCTION and AIM

Psychomotor deficits are more commonly reported among children born preterm (PT) than those born full-term (FT). Further, evidence exists for more covert motor problems in children born preterm at school age [1]. Such findings may be associated with a more immature spatiotemporal model of movements and lower cognitive functioning in children born PT than FT [2]. The main aim of this study was to investigate the effects of gestational age (GA) on uni- and bimanual goal-directed arm movement organization and on cognitive functioning in children at school age.

PATIENTS/MATERIALS and METHODS

Participants consisted of 88 children between 6-9 years of age (M = 7.7 years; 40 PT, 19 girls; 48 FT, 22 girls) without known developmental delays or deviations. Children born PT were divided into two subgroups: moderately PT (M-PT), 34-36 weeks’ gestation (GW), and very PT (V-PT), < 34 GW. Movement kinematics were examined during performance of a goal-directed task, where the participants pushed three buttons in a sequential order in two different directions (vertical or horizontal) with either the right or left hand (unimanual) and with both hands simultaneously (bimanual). Movements were recorded by a 6-camera movement registration system (240Hz, ProReflex) and the number of movement units (MUs) was derived from head, shoulders, elbow, and wrist movement velocity profiles. Cognitive function in terms of verbal IQ (VIQ) and full scale IQ (FSIQ) was measured by the Wechsler Intelligence Scale for Children, 4th edition (WISC-IV).

RESULTS

Overall, a significant difference between the groups regarding number of MUs and FSIQ was found. In general, children born V-PT showed more MUs compared with the FT and M-PT group. Regardless of group, a significant higher amount of MUs was found in the bimanual condition than in the unimanual, and during horizontal movement performance in comparison with vertical. Furthermore, GA was significant negatively correlated with number of MUs for right and left wrist and right elbow, and also with FSIQ.

DISCUSSION and CONCLUSIONS

These findings suggest that lower GAs are associated with both more segmented goal-directed arm movements as well as with lower general cognitive ability. During the more demanding tasks, i.e. bimanual and horizontal movements, this association became particularly evident, where the children born V-PT exhibited the greatest difficulties. Thus, this indicate immature spatio-temporal movement organization as a long-lasting effect of risk factors associated with a preterm birth, specifically for children born V-PT, that may be related to lower cognitive function. Further, limitations in kinematic degrees of freedom, leading to restricted amounts of solutions when solving a motor task, may also partly explain these findings.

REFERENCES

[1] Bracewell, M. & Marlow, N. (2002). Patterns of motor disability in very preterm children. Mental Retardation and Developmental Disabilities Research Reviews, 8(4), 241-248.

[2] Domellöf, E., Johansson, A-M., Farooqi, A., Domellöf M. & Rönnqvist, L. (2013). Relations among upper-limb movement organization and cognitive function at school age in children born preterm. Journal of Developmental & Behavioral Pediatrics, 34(5), 344-352.