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Longitudinal changes in cortical grey matter in adolescents with developmental language disorder
Poster Session C, Saturday, September 13, 11:00 am - 12:30 pm, Field House
Nilgoun Bahar1,2, Saloni Krishnan3, Kate E. Watkins1; 1University of Oxford, UK, 2University of California San Francisco, USA., 3University College London, UK
Introduction: Developmental language disorder (DLD) affects approximately 7% of children, leading to persistent difficulties in learning language without a known cause. Cross-sectional neuroimaging studies have found atypical grey matter morphology in peri-sylvian regions bilaterally in DLD, but the developmental trajectories underlying these findings remain unclear. Longitudinal studies are needed to determine whether the grey matter differences in DLD persist over time, therefore “lagging” the changes in typical development, or if they reflect a delay that eventually reaches the same level of maturation. A third possibility is that the trajectories of cortical change in DLD deviate from those in typical development. Methods: In a longitudinal investigation, we collected T1-weighted structural MRI scans and extensive neuropsychological data from 53 children and adolescents, who were first assessed between ages 10–15 and followed up between 14–20 years old, with a mean interval of 4 years 6 months. Participants included 20 who met our criteria for DLD, 22 typically developing (TD) controls, and 11 with a history of speech-language difficulties (HSL) who did not meet DLD criteria. Using FreeSurfer-derived cortical metrics, we estimated changes in cortical surface area and thickness in 84 structural scans collected at two time points from the DLD and TD groups. Results: Behaviourally, at initial assessment, participants with DLD performed poorer than their TD peers on all measures of language, memory, reading, nonverbal reasoning, and motor control. At follow-up, the gap in performance between DLD and TD persisted, despite similar rates of gain in both groups on most tests. The performance of HSL participants typically fell between the other two groups. Brain imaging analyses indicated reductions in surface area in the superior temporal sulcus and ventromedial prefrontal cortex bilaterally in both DLD and TD groups over time. Additionally, the TD group showed surface area reductions in the left ventral postcentral gyrus, which remained unchanged in DLD. The DLD group, on the other hand, showed an increase in surface area in the left pars opercularis and anterior insula, and in the temporal pole bilaterally. These regions were not significantly changed in the TD group. Cortical thickness reductions (thinning) were observed in both groups in association cortex, consistent with previous longitudinal studies of typical development. Discussion: The behavioural results indicate that individuals with DLD have qualitatively similar but quantitatively lower performance on a range of cognitive skills that continues into adolescence and early adulthood. This pattern reflects a persistent lag in development of language and other skills. The imaging results suggest dynamic and region-specific patterns of cortical maturation in DLD, likely reflecting complex interactions between synaptic pruning, myelination, and experience-dependent plasticity. Regional differences aligned with distinct maturational profiles; the left ventral postcentral cortex showed evidence of lagged development in DLD, while the left frontal opercular cortex appeared more consistent with a delayed maturation trajectory. However, with the current two time-point design we were sensitive to linear changes only. Longitudinal data spanning a wider age range and incorporating multiple time points from larger samples will be required to characterise brain trajectories in this population.
Topic Areas: Disorders: Developmental, Language Development/Acquisition