24-hour movement-behavior guideline attainment and school functioning in children with and without co-occurring ADHD and learning disability: evidence from the NSCH 2018–2024

Twenty-four-hour movement behaviors, including physical activity, recreational screen time, and sleep, have been linked to child health and functional outcomes. However, most studies have examined general populations or single-diagnosis groups. We examined the association between 24-hour movement-behavior guideline attainment and school-related functioning in U.S. children, using ADHD × learning disability (LD) cross-classification to distinguish the overall movement-behavior gradient from diagnostic differences in baseline functioning. We analyzed pooled cross-sectional data from the 2018–2024 National Survey of Children’s Health public-use topical files and included children aged 6–17 years. The survey was completed by parents or caregivers about selected children. Children were classified into four current ADHD/LD groups: neither ADHD nor LD, ADHD-only, LD-only, and ADHD + LD, with explicit handling of questionnaire-design skips and indeterminate current diagnostic status. The exposure was the number of 24-hour movement-behavior guidelines met, from 0 to 3. Outcomes were higher caregiver-reported school functioning and caregiver-reported school-initiated contact regarding school problems. Survey-weighted logistic regression models adjusted for demographic, socioeconomic, family-structure, and survey-year covariates. Among 209,556 age-eligible children, 206,636 had classifiable current ADHD/LD status. Adjusted analytic samples included 196,143 children for higher school functioning and 197,776 for school-initiated contact regarding school problems. Compared with meeting 0 guidelines, meeting 3 guidelines was associated with higher odds of higher school functioning (OR 3.87, 95% CI 3.50–4.28) and lower odds of school-initiated contact regarding school problems (OR 0.49, 95% CI 0.44–0.54). The favorable graded pattern for higher school functioning appeared across all four ADHD/LD groups, while the ADHD + LD group remained on the lowest functional baseline. A non-monotonic school-contact pattern in the ADHD-only group at 3 guidelines was treated as an exploratory subgroup signal requiring replication. Additional component-specific, pattern-based, original-category, and sequential-adjustment analyses did not materially alter the primary interpretation. Greater 24-hour movement-behavior guideline attainment was associated with more favorable school-related functioning among U.S. school-aged children. ADHD × LD cross-classification added clinically relevant information by separating the overall movement-behavior gradient from persistent diagnostic differences in baseline school-functioning burden. Exploratory variation across strata should be interpreted cautiously.