Gymnastik- och idrottshögskolan, GIH

Background Attention-deficit/hyperactivity disorder (ADHD) symptoms are associated with adverse health outcomes; this may be partially due to unhealthy lifestyle factors such as low physical activity (PA) and high sedentary behavior (SED). However, this association remains unclear. ADHD and PA have a medium-to-high heritability; therefore, genetically informed studies are warranted. This study aimed to increase the understanding of the association between ADHD symptoms and time spent in PA and SED in children. Additionally, we aimed to determine whether sex, symptom type, and genetics influence this association. This could guide the design of health promotion and preventive interventions.Methods This cross-sectional twin study included 9-year-old children from the Swedish Twin Registry born from 2011 to 2015 who had complete data on ADHD symptoms and accelerometry. ADHD symptoms were assessed through a parental-report questionnaire. Inattention and hyperactivity/impulsivity symptoms were analyzed together and separately. Triaxial accelerometry measured the average time (minutes) spent in SED, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA). Linear generalized estimating equations regression models were used to assess the association in the full cohort and stratified by sex. Within-twin pair analyses were performed separately for dizygotic and monozygotic twins. Regression coefficients and 95% confidence intervals (CI) were calculated.Results 1966 children (52.8% girls) were included. In the full cohort, ADHD symptoms were significantly associated with less time in SED (beta = -0.32; 95% CI -0.59, -0.06) and more time in MVPA (beta = 0.30; 95% CI 0.12, 0.47). These associations were primarily driven by hyperactivity/impulsivity symptoms and were significant only in girls. The associations remained in dizygotic twins but became non-significant among monozygotic twins.Conclusion Our findings suggest that in girls, higher hyperactivity/impulsivity symptoms are associated with higher PA levels. Associations were largely explained by shared familial factors, including genetics. Longitudinal studies are needed to corroborate these results.