This study looked at 1,966 nine-year-old twins in Sweden, born 2011 to 2015. Just over half were girls (52.84%). Parents rated ADHD symptoms, and each child wore a hip movement sensor for 4 to 9 days. The study treated ADHD symptoms as a scale across the general population, not as a diagnosis. The main analyses used 1,936 children.
Children with more ADHD symptoms had less sedentary (still) time and more moderate to vigorous activity. Once the researchers took each child's sex into account, this overall link was no longer clear. The link with hyperactive and impulsive symptoms still held after that adjustment. Symptoms of inattention showed no clear link with activity.
When girls and boys were analyzed separately, the links appeared only in girls. In boys, none were clear.
The study also compared twins within the same pair. The link with hyperactive symptoms held in non-identical twins. In identical twins it weakened and was no longer clear. The authors read this as a sign that shared family factors, including genes, largely explain the link.
The study measured each child once, so it cannot show which came first. Only 30% of eligible children agreed to wear the sensor, and those who did had fewer ADHD symptoms than those who did not. All the children were twins born in Sweden, and maternal education was high. Medication use could not be taken into account.
The numbers Stats and what the terms mean
The statistics behind the plain-language claims above.
- Ontiveros, 2026: change in daily sedentary time for each extra point of total ADHD symptoms, adjusted for wear time (n = 1936), −0.32 min/day (95% CI −0.59, −0.06; p = 0.015).
- Ontiveros, 2026: change in daily moderate to vigorous activity for each extra point of total ADHD symptoms, adjusted for wear time, 0.30 min/day (95% CI 0.12, 0.47; p < 0.001).
- Ontiveros, 2026: the same sedentary link after also adjusting for sex, SED −0.23 (95% CI −0.50, 0.03; p = 0.092).
- Ontiveros, 2026: the same activity link after also adjusting for sex, MVPA 0.15 (95% CI −0.02, 0.32; p = 0.084).
- Ontiveros, 2026: hyperactive and impulsive symptoms and sedentary time, after adjusting for sex, SED −0.87 (95% CI −1.54, −0.19; p = 0.011).
- Ontiveros, 2026: hyperactive and impulsive symptoms and moderate to vigorous activity, after adjusting for sex, MVPA 0.62 (95% CI 0.20, 1.04; p = 0.003).
- Ontiveros, 2026: total ADHD symptoms and sedentary time in girls only, −0.59 min SED (95% CI −0.97, −0.20; p = 0.002).
- Ontiveros, 2026: total ADHD symptoms and moderate to vigorous activity in girls only, 0.34 min MVPA (95% CI 0.10, 0.58; p = 0.004).
- Ontiveros, 2026: hyperactive and impulsive symptoms and sedentary time in girls only, −1.68 min SED (95% CI −2.66, −0.70).
- Ontiveros, 2026: hyperactive and impulsive symptoms and moderate to vigorous activity in girls only, 1.03 min MVPA (95% CI 0.45, 1.61). What the terms mean:
- SED Sedentary time, meaning time spent still.
- MVPA Moderate-to-vigorous physical activity.
- n The number of children in that analysis.
- 95% CI The range of values the data are consistent with; if it crosses zero, the link is not clear.
- p How likely a result this strong would be if there were no real link; below 0.05 is usually read as unlikely to be down to chance.
Source: Narda Ontiveros, Björg Helgadóttir, Örjan Ekblom, et al.. Association between ADHD symptoms and device‐measured physical activity and sedentary behavior in childhood: A population‐based twin study. JCPP Advances (2026). doi:10.1002/jcv2.70141