Localized cortical morphometric and structural covariance differences in adolescents with functional/dissociative seizures

Abstract

Abstract

OBJECTIVE: Functional/dissociative seizures (FDS) frequently emerge during adolescence. We examined whether adolescents with FDS show cross-sectional differences in cortical morphometry and structural covariance relative to healthy controls. METHODS: High-resolution T1-weighted magnetic resonance imaging data were acquired from 150 adolescents (75 with FDS, 75 healthy controls) recruited between 2021 and 2024. Surface-based morphometry was used to derive cortical thickness, fractal dimension, gyrification index, and sulcal depth. Structural covariance networks were constructed for cortical thickness and fractal dimension across 68 cortical regions from the Desikan-Killiany atlas. Regional analyses were corrected for false discovery rate, and global graph metrics were summarized as area under the curve across a predefined sparsity range with permutation testing. A follow-up region of interest (ROI)-wise analysis additionally included education as a covariate. RESULTS: Adolescents with FDS showed distributed differences involving frontal, insular, cingulate, temporal, parietal, and posterior associative cortices. Strongest effects included increased cortical thickness in the left pars opercularis (t = 3.485, corrected p = .000341, Hedges g = .57), reduced sulcal depth in the left precentral cortex (t = -3.683, corrected p = .000115, g = -.60), and reduced gyrification in the right insula (t = -3.167, corrected p = .000968, g = -.52). Fractal dimension (FD) covariance showed broader descriptive between-group divergence than cortical thickness (CT) covariance. CT-FD consensus analysis identified convergent covariance differences involving frontoparietal, cingulate, and occipitoparietal regions. After education adjustment, no cortical thickness ROI survived false discovery rate correction, whereas six fractal dimension ROIs remained significant: left medial orbitofrontal, left precentral, left banks of the superior temporal sulcus, right rostral middle frontal, left cuneus, and right caudal anterior cingulate cortices (t = -3.6755 to 3.1502, q = .0126-.0487). Global graph analysis did not detect robust differences. SIGNIFICANCE: Adolescent FDS are associated with regional cortical morphometric alterations and modality-specific structural covariance differences, whereas robust differences in global structural covariance topology were not observed.