Long-term bidirectional association between asthma and attention deficit hyperactivity disorder: A big data cohort study.

Background: Previous studies have argued that attention deficit hyperactivity disorder (ADHD) is associated with asthma. However, reliable evidence to verify this association has not yet been reported.

Objectives: To investigate the bidirectional association between asthma and ADHD through a 12-year big data cohort study.

Association between complementary food introduction before age 4 months and body mass index at age 5-7 years: A retrospective population-based longitudinal cohort study.

Background: The optimal time of starting complementary foods (CFs) in infants remains a subject of debate. This population-based longitudinal cohort study evaluated the association between early CF introduction and body mass index (BMI) in children aged 5-7 years.

Methods: The present study included 917,707 children born in Korea during 2008-2009.

Neurodevelopmental Outcomes in Infants Fed with Soy Formula: A Retrospective, National Population-Based Observational Cohort Study.

Background: Soy-based infant formulas are increasingly popular, but data regarding their effects on neurodevelopmental outcomes during early childhood is scanty.

Objective: This study investigated the effect of consuming soy-based infant formula at 9-12 mo after birth on the subsequent development of epilepsy, neurodevelopmental disorders, and developmental status.

Methods: This nationwide retrospective administrative study used health screening examinations and linked insurance claims data of children born in Korea during 2008 and 2009.