Abstracts

Rationale: Parents report normal social skills in siblings of children with epilepsy (S-CWE) but poor social skills in the probands. Normal or problem social behaviors in the siblings of children with a chronic illness or disability are usually attributed to psychosocial factors (e.g., coping skills, parenting, and family functioning). This is the first study to examine if social problems and poor peer interaction are related to biological factors in S-CWE. It compared parent reports of peer interaction and social problems and the relationship of these social measures with fronto-temporal volumes in S-CWE and healthy contols (HC) subjects. Methods: : 38 S-CWE, aged 10.3 (2.67) years, and 36 HC subjects, aged 10.5 (2.56) years, underwent MRI scans at 1.5T. Tissue was segmented and total brain, frontal lobe, frontal parcellations (inferior frontal gyrus (IFG), orbital frontal gyrus (OFG), dorsolateral prefrontal cortex (DLPFC)), and temporal lobe (TL) gray and white matter volumes (GMV, WMV) were computed. Parent Child Behavior Checklists yielded social problem and peer interaction scores. A social composite Z score was constructed by taking an average of the z-transformed peer interaction and social problem scores. (Social problems scores were inverted so that increasing scores represented fewer problems.) ANCOVAs, controlling for age and gender, were used to determine group differences in social scores and volumetric measures. General linear models, with the regional volumes as the dependent variables and group, social score and interaction of group and social scores as predictors, were estimated to determine if the two groups differed in the relationships between volumetric measures and social scores. Results: The S-CWE exhibited significantly lower peer interaction scores and social composite Z scores compared to the HC but there were no significant differences in the mean social problem scores and fronto-temporal volumes. A significant group x social score interaction was observed for TL GMV (F(1, 57) 12.0, p = .001), TL WMV (F(1, 58) 5.3, p = .02), and OFG WMV (F(1, 55) 6.2, p = .02). The social Z score was significantly and negatively related to right (r = -.53, p = .003) and left (r = -.46, p = .01) TL GMV in the HC but not in the S-CWE. The social Z scores were negatively related to right TL WMV (r = -.32, p = .09) in the HC and positively related in the S-CWE (r = .32, p = .08), but the associations were of borderline significance. The social Z score of the S-CWE group also correlated significantly with right OFG WM volumes (r = -.39, p = .04) but not in the HC. Conclusions: This is the first study to identify that the social difficulties of S-CWE are related to structural abnormalities in the right OFG, a brain region involved in the integration of factual and emotional information, regulation of social decision-making, and emotional regulation.