IN ADOLESCENTS, higher levels of self-reported unsupervised physical activity from childhood were linked to poorer working memory, while higher screen time was linked to better overall cognition, according to a new cohort study.
Evidence on the relationship between sedentary time and cognition has remained mixed, with a lack of device-assessed measurements and limited contextualisation of sedentary activities in previous research. How cumulative exposure to physical activity, sedentary time, and screen time from childhood to adolescence relates to cognition has remained an important gap in youth health research.
Researchers analysed data from 260 adolescents aged 15 to 17 years at an eight-year follow-up as part of the PANIC study. Physical activity and sedentary time were assessed both objectively, via an Actiheart movement and heart-rate sensor, and subjectively, via questionnaires. Screen time, however, was assessed by questionnaire only, with no corresponding device-based measure. Cognition was assessed at eight years using the CogState battery, covering psychomotor function, attention, working memory, and paired-associate learning.
Self-reported cumulative unsupervised physical activity from childhood to adolescence was inversely associated with accuracy in a working memory task (standardised regression coefficient β=−0.127, 95% CI −0.247 to −0.008). Self-reported nonscreen-based sedentary time was inversely associated with reaction time (β=−0.176, 95% CI −0.299 to −0.053) and accuracy (β=−0.149, 95% CI −0.274 to −0.024) in working memory tasks. Self-reported screen time was inversely associated with reaction time (β=−0.194, 95% CI −0.316 to −0.071) and accuracy (β=−0.233, 95% CI −0.355 to −0.112) in working memory tasks, but directly associated with better overall cognition (β=0.187, 95% CI 0.070 to 0.305).
Associations differed by sex: unsupervised physical activity was linked to poorer working memory in boys but not girls, while device-assessed light physical activity was linked to better working memory in girls but not boys.
Device-assessed activity and sedentary time overall showed no association with cognition, unlike the self-reported measures; this discrepancy suggests the self-reported findings may partly reflect how adolescents perceived their own behaviour rather than their objectively measured activity levels.
These findings have suggested that accumulating less unsupervised physical activity and more screen time from childhood to adolescence was associated with better cognition in this cohort. As this was an observational study relying substantially on self-reported measures, causality cannot be established. The authors have called for future studies to repeatedly assess physical activity, sedentary time, and cognition together to better establish these relationships over time.
Reference
Jalanko P et al. Associations of physical activity and sedentary time from childhood to adolescence with cognition in adolescence: The PANIC study. Pediatric Exercise Science. 2026;1(aop):1-6.
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