Microstructural alterations in association tracts and language abilities in schoolchildren born very preterm and with poor fetal growth

Abstract

Background Prematurity and perinatal risk factors may influence white matter microstructure. In turn, these maturational changes may influence language development in this high-risk population of children. Objective To evaluate differences in the microstructure of association tracts between preterm and term children and between preterm children with appropriate growth and those with fetal growth restriction and to study whether the diffusion tensor metrics of these tracts correlate with language abilities in schoolchildren with no severe neurological impairment. Materials and methods This study prospectively followed 56 very preterm children (mean gestational age: 28.7 weeks) and 21 age- and gender-matched term children who underwent diffusion tensor imaging at a mean age of 9 years. We used automated probabilistic tractography and measured fractional anisotropy in seven bilateral association tracts known to belong to the white matter language network. Both groups participated in language assessment using five standardised tests at the same age. Results Preterm children had lower fractional anisotropy in the right superior longitudinal fasciculus 1 compared to term children (P < 0.05). Preterm children with fetal growth restriction had lower fractional anisotropy in the left inferior longitudinal fasciculus compared to preterm children with appropriate fetal growth (P < 0.05). Fractional anisotropy in three dorsal tracts and in two dorsal and one ventral tract had a positive correlation with language assessments among preterm children and preterm children with fetal growth restriction, respectively (P < 0.05). Conclusion There were some microstructural differences in language-related tracts between preterm and term children and between preterm children with appropriate and those with restricted fetal growth. Children with better language abilities had a higher fractional anisotropy in distinct white matter tracts.

Neuroimaging of brain connectivity related to reading outcomes in children born preterm: A critical narrative review

“…Of particular interest in many studies of PT are the classical dorsal and ventral tracts associated with reading outcome in TC. In general, negative associations were found between FA of these pathways (left sided SLF, AF, bilateral UF, bilateral CST) and reading outcome in TC while positive associations are seen with the same tracts and reading outcome in PT (82,86,87,89). One explanation of the negative correlations with reading outcome might be that, in TC, pruning leads to decreased FA in important areas as efficiency increases, such that initial positive associations between FA and ability become negative associations in later years.…”

“…In VPT, increasing FA of the left AF and bilateral SLF positively related to rapid naming scores. Rapid naming is an important factor in reading ability (82,83). FA of left SLF (branches 2, 3) was positively associated with verbal comprehension and spelling scores.…”

“…In VPT only, reading scores were positively correlated with FA of diffuse fiber tracts including the cerebellar peduncles, Most studies evaluating white matter tracts related to reading have been performed in cohorts of older children in later stages of reading development (conventional literacy phase) with a focus on a-priori selected tracts. A Finnish cohort study of 9year-old VPT and TC correlated DTI with reading fluency, comprehension, rapid naming, word reading, verbal comprehension and spelling (82). In VPT, increasing FA of the left AF and bilateral SLF positively related to rapid naming scores.…”

“…Of the 22 studies evaluated in this review, 14 stem from one of these 3 cohorts, as do all the case reports mentioned. The remaining 8 studies include 3 from a single Australian cohort (80,81,91), 2 from a Houston cohort (84, 97), and 3 individual studies unrelated to other cohorts (82,93,96). It is possible that the results obtained thus far will not generalize given the relatively limited number of children studied.…”