Abstracts

Rationale: About one-fifth of children with epilepsy with average intellectual skills have suicidal ideation, particularly those with disruptive disorder diagnoses (Caplan et al., 2005). Disruptive disorders and impulsivity are also found in the general population of youth with suicidal behavior (Brent et al., 2003). Smaller gray and white matter orbital frontal volumes in depressed women with suicidal behavior (Monkul et al., 2006), the role of this brain region in impulsivity (Happaney et al., 2004), and decreased orbital frontal gyrus and temporal lobe gray matter volumes in pediatric epilepsy (Caplan et al., 2009; Daley et al., 2007) underlie the rationale for this study. We examined orbital frontal gyrus and temporal lobe gray and white matter volumes in children with epilepsy with and without suicidality. Methods: Fifty-one children with epilepsy aged 5.1-16.3 years had MRI scans at 1.5 Tesla. Tissue was segmented and total brain, frontal lobe, frontal parcellations and temporal lobe volumes were computed. Structured psychiatric interviews, administered to all children and their parents separately, provided information on current and past suicidaity and DSM-IV diagnoses. Parents provided information on seizure variables. Results: Other than older age (Wilcoxon test statistic = 382, exact p=.03) and longer duration of illness (Wilcoxon test statistic = 372, exact p=.05) in the 11 subjects with suicidal ideation compared to the 40 without, there were no significant between group differences on demographic and seizure variables, including number of antiepileptic drugs (AEDs). Mixed general linear models comparing epilepsy subjects with and without suicidal ideation, controlling for age and total brain volume, revealed a significant finding for orbital frontal white matter volumes (F(1,47)=4.89, p=.03) and a trend for temporal lobe gray matter volumes (F(1,47)=3.49, p=.07). Post-hoc analyses demonstrated significantly smaller right orbital frontal white matter volumes (F(1,47)=5.61, p=.02) and larger left temporal gray matter volumes (F(1,47)=4.42, p=.04) in the children with suicidal ideation compared to those without suicidality. Conclusions: These findings suggest that impairment in the normal age-related myelination of the right orbital frontal gyrus and pruning of temporal lobe gray matter (Lenroot and Giedd, 2006) might underlie suicidal ideation in older children with epilepsy with longer duration of illness. Given similar number of AEDs in the children with and without suicidal ideation, these developmental brain volume findings challenge the recent FDA conclusions on AEDs and suicide in epilepsy. The high rate of disruptive disorder diagnoses and orbital frontal gyrus involvement also indirectly support theories on the role of impulsivity in suicidality (Brent et al. 2003).