Prevalence and factors of sleep problems among Japanese children: a population-based study.

Background: High prevalence of sleep problems in not only children with neurodevelopmental disorders (NDS) but also non NDS has been established. However, there are few studies that have looked into population-based and age-specific prevalence of sleep problems of children. Moreover, there are even fewer studies that have investigated the correlation of demographic and lifestyle-related factors affecting sleep problems in children. Considering these, the purpose of this study is to assess the correlation of the prevalence of sleep problems and selected socio-demographic and lifestyle-related factors in 5-year-old Japanese children in population-based study. Methods: Study children (SC) were recruited from two cohorts of the Hirosaki City 5-Year-Old Child Developmental Health Checkup Study. The first cohort consisted of 281 (162 males, 119 females) children recruited from 2014 to 2015, and the second cohort consisted of 2055 (1,068 males, 987 females) children from 2018 to 2019. In total there were 2,336 SC participants (1,230 males and 1,106 females). To determine the prevalence of sleep problems the Japanese Sleep Questionnaire for Preschoolers (JSQ-P) was utilized, and sleep problems are defined by a total score of ≥86. To determine socio-demographic and lifestyle-related factors affecting sleep, 10 factors (NDS diagnosis, birth month, childcare place, income, number of siblings, bedtime, waking time, sleeping hours, sleep onset delay, and screen time) were selected. Finally, to determine the correlation between prevalence of sleep problems and the selected demographic and lifestyle-related factors, data was analyzed using chi-square test. Results: The prevalence rate of sleep problems in 5-year-olds was 18% (369/2,055). Further, the prevalence of sleep problems was high in participants with ASD (50.4%), ADHD (39.8%), <2 million yen of income (30.5%), no siblings (24.2%), >22:00 of bedtime (30.7%), >7:30 of waking time (30.7%), <9 h of sleeping hours (25.3%), >30 min of sleep onset delay (35.3%), and ≥2 h of screen time (21.1%). Conclusion: The findings report 18% prevalence rate of sleep problems in 5-year-old children. Further, the findings establish a significant correlation of sleep problems and NDS, specific socio-demographic, and lifestyle-related factors. In considering the identified modifiable lifestyle-related factors contributing to sleep problems among the participants (i.e., bed/waking times and screen times), sleep programs to address these concerns are suggested.

Copy number variations in Japanese children with autism spectrum disorder.

OBJECTIVE: Although autism spectrum disorder (ASD) occurs worldwide, most genomic studies on ASD were performed on those of Western ancestry. We hypothesized ASD-related copy number variations (CNVs) of Japanese individuals might be different from those of Western individuals. METHODS: Subjects were recruited from the Hirosaki 5-year-old children's developmental health check-up (HFC) between 2013 and 2016 (ASD group; n = 68, control group; n = 124). This study conducted CNV analysis using genomic DNA from peripheral blood of 5-year-old Japanese children. Fisher's exact test was applied for profiling subjects and CNV loci. RESULTS: Four ASD-related CNVs: deletion at 12p11.1, duplications at 4q13.2, 8p23.1 and 18q12.3 were detected (P = 0.015, 0.024, 0.009, 0.004, respectively). Specifically, the odds ratio of duplication at 18q12.3 was highest among the 4 CNVs (odds ratio, 8.13). CONCLUSIONS: Four CNVs: microdeletion at 12p11.1, microduplications at 4q13.2, 8p23.1 and 18q12.3 were detected as ASD-related CNVs in Japanese children in this study. Although these CNVs were consistent with several reports by Western countries at cytoband levels, these did not consistent at detailed genomic positions and sizes. Our data indicate the possibility that these CNVs are characteristic of Japanese children with ASD. We conclude that Japanese individuals with ASD may harbor CNVs different from those of Western individuals with ASD.

Psychometric properties of the Japanese ADHD-RS in preschool children.

BACKGROUND: Children with ADHD show multiple difficulties in their lives. Its early detection is important to provide timely intervention. AIMS: To evaluate the psychometric properties of the Japanese version of the home and school form of the ADHD-Rating Scale-IV (P- and T-ADHD-RS) for screening five-year-olds with ADHD. METHODS: The parents and teachers of 838 children (452 boys, 386 girls; including 28 boys, 18 girls diagnosed ADHD) completed the ADHD-RS and the Strengths and Difficulties Questionnaire in a community health check-up. RESULTS: The P- and T-ADHD-RS confirmed the two-factor model (Inattention and Hyperactivity-Impulsivity) and internal consistencies (CFI=0.968, 980; RMSEA=0.049, 0.055; SRMR=0.030, 0.024; α=0.86-.93). Japanese boys and girls scored significantly lower in all scales of the P- and T-ADHD-RS (d=0.65-1.14, 0.36-0.59) than US children. The P-ADHD-RS showed higher accuracy in area under the curve (AUC), sensitivity, and positive predictive value (PPV) than the T-ADHD-RS (AUC=0.955, 0.692; sensitivity=89.13%, 30.23%; PPV=46.59%, 16.05%). IMPLICATIONS: The P-ADHD-RS shows good reliability and validity for screening children with possible ADHD in a community. Longitudinal studies are needed to examine its predictive validity of adaptation in their lives at school.