A crucial role of altered fractional anisotropy in motor problems of very preterm children.

Background: Very preterm children (<32 weeks of gestation) are characterized by impaired white matter development as measured by fractional anisotropy (FA). This study investigates whether altered FA values underpin the widespread motor impairments and higher incidence of developmental coordination disorder (DCD) in very preterm children at school-age.

Methods: Thirty very preterm born children (mean (SD) age of 8.6 (0.3) years) and 47 term born controls (mean [SD] age 8.7 [0.5] years) participated. Motor development was measured using the Movement Assessment Battery for Children. A score below the 15th percentile was used as a research diagnosis of DCD. FA values, as measure of white matter abnormalities, were determined for 18 major white matter tracts, obtained using probabilistic diffusion tensor tractography.

Results: Large-sized reductions in FA of the cingulum hippocampal tract right (d = 0.75, p = .003) and left (d = 0.76, p = .001), corticospinal tract right (d = 0.56, p = .02) and left (d = 0.65, p = .009), forceps major (d = 1.04, p < .001) and minor (d = 0.54, p = .02) were present in very preterms, in particular with a research diagnosis of DCD. Reduced FA values moderately to strongly related to motor impairments. A ROC curve for average FA, as calculated from tracts that significantly discriminated between very preterm children with and without a research diagnosis of DCD, showed an area under curve of 0.87 (95% CI 0.74-1.00, p = .001).

Conclusions: This study provides clear evidence that reduced FA values are strongly underpinning motor impairment and DCD in very preterm children at school-age. In addition, outcomes demonstrate that altered white matter FA values can potentially be used to discriminate between very preterm children at risk for motor impairments, although future studies are warranted.