Background: Despite evidences of breastfeeding for preventing acute physical illnesses in infants, the evidence for the association between breastfeeding and long-term cognitive development is not yet convincing.Methods: The data of nationwide representative sample of 1752 children born between 2008 and 2009 in Korea were prospectively assessed from the fetal period to examine the benefits of breastfeeding and cognitive development. Breastfeeding duration was prospectively assessed by parents. The Korean Ages and Stages Questionnaire and the Korean version of Denver II were used to assess early development annually from 5.5 to 26.2 months of age. Language development at 3 years of age was assessed with Receptive and Expressive Vocabulary Tests. Cognitive function at 8 years of age was assessed using multifactorial intelligence test.Results: In the analysis of categorical variables, children who were breastfed for > 1 and ≤ 3 months displayed significantly higher odds ratios for delayed development assessed with Korean Ages and Stages Questionnaire at 14.1 months than those breastfed for > 3 and ≤ 6 months (OR = 2.21; 95% CI: 1.08, 4.50), but no significant differences in other rounds of assessments. In the analysis with continuous variables, there were significant differences among six groups of breastfeeding duration in communication (F = 3.72;p < 0.002) and problem solving (F = 3.09;p < 0.009) at 14.1 months, expressive language (F = 3.74;p = 0.002) at 3 years, and calculation (F = 2.43;p < 0.033) at 8 years. When analyzed by two groups, children breastfed for > 3 months scored significantly higher on the communication (F = 17.71;p < 0.001) and problem-solving (F = 11.26;p < 0.001) subscales at 14.1 months, and expressive language (F = 12.85;p < 0.001) at 3 years, and vocabulary (F = 6.78;p = 0.009) and language inference (F = 5.62;p = 0.018) at 8 years, compared to children breastfed for 3 months or less.Conclusion: We found that cognitive development was improved in children that were breastfed for > 3 months. Although these results are supported by previous studies, it is important to note that other factors were reported as larger determinants of cognitive development than breastfeeding. Future studies that examine the underlying mechanism for the association between breastfeeding and cognitive development are warranted.

Purpose: This study investigated the prevalence and correlates of problematic internet use (PIU) in a large sample of adolescents based on the type of internet service used. Materials and Methods: The study was conducted from 2008 to 2010, and 223,542 adolescents aged 12 to 18 years participated in the study. The participants responded to a self-report questionnaire including items for demographic factors, internet usage time, most used internet service and mental health. The PIU was assessed with the Internet Addiction Proneness Scale for Youth-Short Form. Results: The overall prevalence rate of PIU was 5.2%, and the prevalence rates stratified by sex were 7.7% in boys and 3.8% in girls. The distribution of most used internet services was significantly different across sexes. The most commonly used internet services were gaming (58.1%) in boys and blogging (22.1%) and messenger/chatting (20.3%) in girls. The odds ratio for PIU was significantly different according to the most used internet service; using the internet mostly for pornography compared to information searching had the highest odds ratio (4.526-fold higher). Depressive episodes, suicidal ideation, and suicidal attempts were significantly associated with higher odds ratios for PIU (1.725-, 1.747- and 1.361-fold, respectively). Conclusion: The present study identified clinically important information about PIU in adolescents. The distribution of PIU has different patterns based on sex and specific internet services. Studies of PIU with well-defined methodology and assessment tools for PIU of each specific internet service are needed.

Bisphenol A (BPA) is a widely produced synthetic chemical used to manufacture polycarbonate plastics and epoxy resins. We aimed to investigate the association between exposure to BPA and behavioral and cognitive function in children with attention-deficit/hyperactivity disorder (ADHD) and healthy controls. The study included 444 children aged from 6 to 10 years. The ADHD and control groups included 195 and 249 children, respectively. BPA levels were assessed via urinalysis, while behavior was assessed using the Korean version of the ADHD Rating Scale (K-ARS) and the Behavior Assessment System for Children (BASC-2). Cognitive function was assessed using the Continuous Performance Test (i.e., ADHD Diagnostic System [ADS]). Participants were categorized into tertile groups based on urinary BPA concentration. Scores on the K-ARS and the hyperactivity, aggression, anxiety, and depression subscales of the BASC-2 were significantly different among tertile groups for urinary BPA levels. Scores on visual omission error, commission error, response time variability, and auditory commission error of the ADS were significantly different among three BPA groups. Subgroup analysis revealed that these differences of behavior and cognition among three BPA groups were observed in only boys and normal controls. Exposure to BPA was associated with unfavorable behavioral and cognitive outcomes. Our study extends the findings of previous studies regarding the association between BPA exposure and behavior/cognitive function by including children with ADHD. Further studies are required to determine the mechanisms underlying sex- and group-based differences in these associations.

Objective This study aimed to identify the central symptoms of late-life depression using network analysis and the item response theory.Methods A total of 3,472 older adults were enrolled and the Geriatric Depression Scale-15 (GDS-15) was used to evaluate the depressive symptoms. To identify the central symptoms and the network structures among the individual symptoms, the analyses of symptom network structures and item response theory were performed.Results Among items on the GDS-15, “Happy,” “Hopeless,” “Empty,” “Bored,” “Worthless,” and “Good spirits” showed significantly higher strength centrality than the other symptoms. Among all the edges, the edge between “Empty” and “Bored” was the strongest; however, these two symptoms were not connected strongly to other symptoms. In the analysis of item response theory, “Empty,” “Bored,” “Hopeless,” “Worthless,” “Happy,” “Helpless,” and “Satisfied” presented a very high value on the discrimination parameter.Conclusion Our study identified the central symptoms and the network structures among symptoms listed on the GDS-15. Most of central symptoms identified by network analysis and item response theory coincided. Our results suggest that these central symptoms need to be prioritized as highly comorbid symptoms and can contribute to the development of a brief screening tool for the elderly.