Abstract
Previous studies of white matter organization in sensorimotor tracts in developmental coordination disorder (DCD) have adopted diffusion tensor imaging (DTI), a method unable to reconcile pathways with ‘crossing fibres’. In response to limitations of the commonly adopted DTI approach, the present study employed a framework that can reconcile the ‘crossing fibre’ problem (i.e., constrained spherical deconvolution- CSD) to characterize white matter tissue organization of sensorimotor tracts in young adults with DCD. Participants were 19 healthy adults aged 18–46: 7 met diagnostic criteria for DCD (4 females) and 12 were controls (3 females). All underwent high angular diffusion MRI. After preprocessing, the left and right corticospinal tracts (CST) and superior longitudinal fasciculi (SLF) were delineated and all tracts were then generated using both CSD and DTI tractography respectively. Based on the CSD model, individuals with DCD demonstrated significantly decreased mean apparent fibre density (AFD) in the left SLF relative to controls (with large effect size, Cohen's d = 1.32) and a trend for decreased tract volume of the right SLF (with medium-large effect size, Cohen's d = 0.73). No differences in SLF microstructure were found between groups using DTI, nor were differences in CST microstructure observed across groups regardless of hemisphere or diffusion model. Our data are consistent with the view that motor impairment characteristic of DCD may be subserved by white matter abnormalities in sensorimotor tracts, specifically the left and right SLF. Our data further highlight the benefits of higher order diffusion MRI (e.g. CSD) relative to DTI for clarifying earlier inconsistencies in reports speaking to white matter organization in DCD, and its contribution to poor motor skill in DCD.
Highlights
Developmental coordination disorder is a movement disorder that emerges in childhood and persists into adulthood for an estimated 30–70% of those affected (Kirby et al, 2010; Saban and Kirby, 2018)
We observed that mean apparent fibre density (AFD) of the left superior longitudinal fasciculus (SLF) was significantly reduced in those with developmental coordination disorder (DCD), with along tract analysis suggesting that this group difference was accentuated in those portions of the SLF immediately anterior to the arcuate fasciculus
Regardless of this, since ours is the first study to model white matter organization in DCD using constrained spherical deconvolution (CSD) we argue that our data provide one of the more robust accounts of white matter organization in DCD, at least as it pertains to young adults
Summary
Developmental coordination disorder is a movement disorder that emerges in childhood and persists into adulthood for an estimated 30–70% of those affected (Kirby et al, 2010; Saban and Kirby, 2018). A series of recent studies have adopted an array of medical imaging techniques to uncover the neural basis of DCD (Biotteau et al, 2016; Fuelscher et al, 2018; Gomez and Sirigu, 2015; Wilson et al, 2017). Only four studies have explored white-matter tract microstructure in DCD (Debrabant et al, 2016; Langevin et al, 2014; Williams et al, 2017; Zwicker et al, 2012) Across these studies, microstructural differences (relative to controls) have been reported in a variety of sensorimotor tracts including the CST, superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus, the internal capsule and corpus callosum (CC). We point towards a number of methodological considerations that have likely contributed to these mixed findings
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