Impaired verbal functioning is linked to altered white matter microstructure in preterm-born adults

Preterm (PT) birth is associated with impaired verbal fluency [1] and verbal processing speed [2]. Interestingly, white matter microstructural alterations in the arcuate fasciculus (AF), superior longitudinal fasciculus (SLF), uncinate fasciculus (UF), and inferior frontooccipital fasciculus (IFOF) -tracts, which are suggested to subserve language ability [3] - have been found in PT-born children [4]. We hypothesized that microstructural alterations of these tracts link with verbal fluency and verbal processing speed impairments in PT-born adults.Sixty-three PT- and eighty-one term-born (FT) adults underwent diffusion-weighted imaging and verbal functioning assessment. Fractional anisotropy (FA) and mean diffusivity (MD) indices were computed as measures of white matter microstructure in the AF, SLF, IFOF, and UF using tract-based spatial statistics. Verbal fluency and verbal processing speed were assessed via the Regensburg word fluency test (RWT) and Rapid Automated Naming Test (RAN) respectively. Two-sample t-tests were used to assess group differences in microstructural measures while their association with verbal functioning scores was assessed via Pearson correlations.We found significantly lower FA and higher MD in IFOF and SLF in PT-born adults. Lower FA was significantly associated with lower gestational age, RWT and RAN scores while higher MD was significantly linked to lower gestational age, RWT and RAN scores.Our findings demonstrate for PT-born adults, long-term microstructural alterations of language-relevant white matter tracts, which link with impaired verbal fluency and processing speed abilities.[1] Tseng et al. doi: 10.1523/ENEURO.0274-18.2018[2] Madzwamuse et al. doi: 10.1111/jcpp.12358[3] Friederici et al. doi: 10.1016/j.conb.2012.10.002[4] Mürner-Lavanchy et al. doi: 10.1016/j.nicl.2018.09.020