Associations between 24 hour movement behaviours and global cognition in US children: a cross-sectional observational study.

Background: Childhood and adolescence are crucial periods for brain development, and the behaviours during a typical 24 h period contribute to cognitive performance. The Canadian 24-Hour Movement Guidelines for Children and Youth recommend at least 60 min physical activity per day, 2 h or less recreational screen time per day, and 9-11 h sleep per night in children aged 8-11 years. We investigated the relationship between adherence to these recommendations and global cognition.

Methods: In this cross-sectional observational study, we obtained data from the first annual curated release of the Adolescent Brain Cognitive Development study, a 10-year longitudinal, observational study. Data were collected from 21 study sites across the USA between Sept 1, 2016, and Sept 15, 2017. The participants were 4524 US children aged 8-11 years from 20 study sites. Exposures of interest were adherence to the physical activity, recreational screen time, and sleep duration guideline recommendations. The primary outcome was global cognition, assessed with the NIH Toolbox (National Institutes of Health, Bethesda, MD, USA), which we analysed with multivariable linear mixed-effects models to examine the relations with movement behaviour variables.

Findings: Complete movement behaviour data were available for 4520 participants. The mean number of guideline recommendations met was 1·1 (SD 0·9). Overall, 2303 (51%) participants met the sleep recommendation, 1655 (37%) met screen time, and 793 (18%) met the physical activity recommendation. 3190 (71%) participants met at least one recommendation, whereas 216 (5%) of participants met all three recommendations. Global cognition was positively associated with each additional recommendation met (β=1·44, 95% CI 0·82-2·07, p<0·0001). Compared with meeting none of the recommendations, associations with superior global cognition were found in participants who met all three recommendations (β=3·89, 95% CI 1·43 to 6·34, p=0·0019), the screen time recommendation only (β=4·25, 2·50-6·01, p<0·0001), and both the screen time and the sleep recommendations (β=5·15, 3·56-6·74, p<0·0001).

Interpretation: Meeting the 24 h movement recommendations was associated with superior global cognition. These findings highlight the importance of limiting recreational screen time and encouraging healthy sleep to improve cognition in children.

Funding: National Institutes of Health.