Potential social-environmental factors affecting ADHD symptoms of 55528 children from Longhua district, Shenzhen, China

Abstract Objective: Attention-deficit hyperactivity disorder (ADHD) is a common childhood behavioral disorder which often persists into adulthood and is correlated with a broad range of other mental or behavioral problems. Some researches have indicated that social-environmental factors could be influential on children with ADHD, but none has a large sample size and most of them lack of data of social-environmental factors from early childhood. Therefore, we aimed to assess the frequency and duration of outdoor activities of preschool-age children at their age of 0–1 and 1–3 and to explore their association with ADHD symptoms. Methods We conducted a retrospective study. We distributed questionnaires to a 59,600 sample of parents of children enrolled in 250 kindergartens in Longhua District, Shenzhen, China. We collected data on sociodemographic characteristics, outdoor activities frequency and duration. We assessed ADHD symptoms with the Strengths and Difficulties Questionnaire (SDQ). Results 55528 valid questionnaires were finally included in the study. The prevalence of ADHD symptoms was 6.9%, with a higher score in boys (3.76 ± 1.96 vs. 3.42 ± 1.87, P  < 0.001). There was a significant difference in ADHD symptoms between high level of household monthly income and low level of household monthly income ( F  = 261.478, P  < 0.001). There was a significant association between higher frequency and duration of outdoor activitiesand lower ADHD symptoms scores ( P  < 0.001). Conclusion Higher frequency and duration of outdoor activities in early childhood may reduce the ADHD symptoms in children. More participation in outdoor activities should be encouraged to manage ADHD symptoms. Continued research should be conducted to better understand the mechanisms behind this association and to tailor interventions to the diverse needs of children with ADHD.