BackgroundPrevious research has suggested that television (TV) viewing may be associated with increased behavioral and emotional problems in children. However, there are few prospective studies targeted for its association with outcomes of children under 3 years old. The purpose of this study was to exam the association between children’s early TV exposure at ages 18 and 30 months and the behavioral and emotional outcomes at age 30 months.MethodsWe analyzed data collected prospectively in the Japan Children’s Study. TV exposure was assessed by mothers’ report at infant ages of 18 and 30 months. The outcomes were assessed using the Strengths and Difficulties Questionnaire (SDQ). Analysis of Covariance was used to estimate the effect of TV exposure on behavioral and emotional outcomes.ResultsThe percentage of children who watched TV 4 hours or more per day was 29.4% at age 18 months, 24.5% at age 30 months, and 21% at both ages. Hyperactivity–inattention at age 30 months was positively associated with TV exposure at age 18 months, whereas prosocial behavior was negatively associated with hours of exposure even after adjustment. However, there were no significant differences in SDQ subscales according to daily hours of TV viewing at age 30 months.ConclusionsDaily TV exposure at age 18 months was associated with hyperactivity–inattention and prosocial behavior at age 30 months. However, the directly casual relation was not proved in the present study. Additional research considering the TV program content and exposure timing are needed to investigate the causal relation between TV viewing and behavioral outcome.

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X-linked lissencephaly with abnormal genitalia (XLAG) is a rare disorder caused by mutations in the aristaless-related homeobox (ARX) gene, located on Xp22.13. Arx-null mice show loss of tangential migration of GABAergic interneurons, presumably being related to caudal ganglionic eminence tangential migration. In the present study, we investigated a subpopulation of GABAergic interneurons in the brain of an infant with XLAG, who had a novel nonsense mutation of the ARX gene, compared with those of age-matched normal controls and Miller-Dieker syndrome. We performed immunocytochemistry for interneuron and migration markers. We found that glutamic acid decarboxylase (GAD)- and calretinin (CR)-containing cells were significantly reduced in the neocortex and located in the white matter and neocortical subventricular zone, while neuropeptide Y- or cholecystokinin-containing cells were normally distributed. Moreover, in the neocortical subventricular region, the GAD- and CR-containing cells expressed the radial migration marker Mash-1 as well as nestin. Our findings suggest that ARX protein controls not only the tangential migration of GABAergic interneurons from the ganglionic eminence, but also may serve to induce radial migration from the neocortical subventricular zone.