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White Matter Microstructure Predicts Language Outcome in Moderate to Late Preterm and Early Term Infants
Poster Session C, Friday, October 25, 4:30 - 6:00 pm, Great Hall 3 and 4
Xiujuan Geng1, Peggy HY Chan, Winnie CW Chu, Hugh S Lam, Patrick CM Wong; 1Chinese University of Hong Kong
INTRODUCTION Moderate to late preterm birth (MLPT) has found to be associated with language developmental delay or deficits. It is not clear how the preterm-related neural pathologies are linked to language development. Previous studies reported white matter differences in very preterm and MLPT infants and white matter microstructure correlations with later language outcomes in very preterm children. We have recently showed that hypomyelination is linked to worse speech encoding in preterm and term babies. In the present study, we further hypothesize that language-associated white matter pathways are affected by prematurity. Importantly, maturation levels around birth are prospectively correlated with later language ability. METHODS One hundred and seven healthy Chinese MLPT and term infants (mean [range] gestation age (GA) at birth: 36.6 [32.0-39.1] weeks) were recruited. Subjects were scanned at approximate two months of chronological age (mean [range]: 9.7 [3.0-18.6] weeks) and during natural sleep on a Siemens Magnetom Prisma scanner. Diffusion-weighted sequences were collected with 46 volumes at multiple b-values (500-2000 s/mm2) and a voxel size of 1.6x1.6x1.8 mm3. Fractional anisotropy (FA) was estimated and spatially normalized to standard space using unbiased nonlinear registration. Tract-based spatial statistics (TBSS) was conducted and statistical analysis was applied on entire brain. Randomise with threshold-free cluster enhancement was used to correct for multiple comparisons and FWE-corrected p-values were reported. Infant’s language ability, including expressive, receptive and composite scores were assessed at 12 months old using Bayley Scales of Infant and Toddler Development III. RESULTS We analyzed the correlations between white matter and language scores controlling for sex and age at scan. Results show that expressive language scores at 1-year-old were significantly positively correlated with FA values in areas along several white matter tracts including left external capsule, uncinate fasciculus, inferior fronto-occipital fasciculus, posterior and retrolenticular part of internal capsule, bilateral superior corona radiata, genu, body and splenium of corpus callosum. To investigate the preterm effect on white matter, we further conducted a GLM with FA=Sex+GA+Age+GA*Age, where GA was the GA at birth. We found that most of the major white matter tracts showed positive correlation between GA and FA. There was also significant negative interaction of GA and Age on FA on bilateral minor forceps, left superior coronal radiata and arcuate fasciculus. CONCLUSIONS We identified that language outcomes at one year of age were associated with white matter integrity/maturation estimated by FA on several tracts including language pathways such as external capsule, superior corona radiata, uncinate fasciculus, inferior fronto-occipital fasiculus measured around 2 months of age. The positive correlation between FA and GA suggests that preterm birth is a risk factor for the maturation of white matter. Moreover, the interaction effect of GA and Age on FA, i.e., the lower the GA, the higher the slope between Age and FA, indicates that preterm babies have a faster maturation speed compared to term babies. Our next step is to test the further hypothesis that the preterm babies who fail to reach term equivalent white matter maturation status are the ones with language developmental delays/deficits.
Topic Areas: Language Development/Acquisition,