Aishah Abdul Rahman

Purpose To examine the longitudinal associations of subjectively-measured physical activity (PA) and screen time with multiple domains of cognitive development in a sample of young children. Methods Participants were 96 children (baseline age: 3.69 ± 0.78 years) and their parents from Edmonton, Canada in the Physical Activity and Cognition in Early Childhood (PACE) study. Different types of PA (organized, non-organized) and screen time (television viewing, video games) were measured using a parental questionnaire at baseline and at 6- and 12-month follow-ups. Total proxy-reported PA, total screen time, and meeting/not meeting the screen time recommendations (2–4 years: ≤1 h/d; 5 years: ≤2 h/d) of the Canadian 24-Hour Movement Guidelines were also calculated. Working memory (Nebraska Barnyard task) and inhibitory control (Fish-Shark Go/No-Go task) were assessed at the three time points. Intellectual ability, including language development, inductive reasoning, and perceptual speed, were assessed using the Woodcock-Johnson III test battery at 6- and 12-month follow-ups. Multilevel growth modeling was conducted. Results Organized PA (B = 1.26; 95%CI: 0.19,2.33), non-organized PA (B = 0.89, 95%CI: 0.08, 1.71), and total proxy-reported PA (B = 1.03, 95%CI: 0.41,1.66) were positively associated with intellectual ability. In particular, positive associations in regard to language development and inductive reasoning were observed. As for screen time, most associations were not significant, except for positive associations of meeting the screen recommendation with intellectual ability (B = 3.19; 95%CI: 0.002,6.38) and language development (B = 4.32; 95%CI: 0.34,8.30). Conclusion For young children, promoting PA participation in organized and non-organized activities, as well as meeting the screen time recommendations, appears important for cognitive development.

When our goals or plans change, we have to be able to flexibly switch to adapt to the current situation or demands. Cognitive flexibility is the mental process that allows us to alternate flexibly and align our behaviours accordingly. Cognitive flexibility emerges in early childhood, but little is known about the neural correlates supporting this ability early in life. In this study, five-year-olds performed the Dimension Change Card Sort (DCCS) task while we recorded their brain activity using scalp-recorded electroencephalography (EEG). As expected, children were slower to respond on trials requiring cognitive flexibility (i.e., post-switch trials). EEG recordings showed that a late occurring frontal negativity (LFN) was larger on post-switch trials than on pre-switch trials. An earlier occurring negativity, the N2, did not differ by switch demands, and was observed on both the pre- and post-switch trials. The findings from this study indicate that as in later stages of development the LFN may be an important neural marker underlying cognitive flexibility in early childhood.

Importance Sedentary behaviour and physical activity are important to consider for optimal cognitive development. Few studies have examined patterns (i.e., bouts/breaks) of these behaviours in early childhood and longitudinal associations with cognitive outcomes. Objectives Examine: 1) changes in total duration and patterns of sedentary time and physical activity across three time-points, separated by approximately six-months; and 2) longitudinal associations of sedentary time and physical activity (i.e., duration and patterns) with cognitive development in early childhood. Method Participants included 100 children aged 2.5–5.0 years at time-point 1. Participants wore ActiGraph accelerometers and completed measures of cognition: inhibitory control (Fish-Shark Go/No-Go task), working memory (Nebraska Barnyard task), and general cognitive ability (Woodcock-Johnson III test battery) at two/three time-points. Multilevel growth modelling was used to examine total duration and patterns (i.e., bouts and breaks) of sedentary behaviour and physical activity over time and longitudinal associations with cognitive outcomes. Results Total sedentary time decreased (β [95% CI] = −9.24 [-15.76, −2.72]; β represents estimated change per year), whereas time spent in moderate-to-vigorous-intensity physical activity (MVPA; 5.65 [1.89, 9.41]) increased over time. A significant decrease in time spent in ≥10-min sedentary bouts (−9.76 [-13.56, −5.96]), and significant increases in sedentary breaks (13.41 [7.18, 19.63]) and time spent in 1-3-min (2.56 [0.96, 4.15]) and 3-5-min bouts of MVPA (0.86 [0.33, 1.38]) were also found. There was minimal evidence of longitudinal associations between the accelerometry variables and cognitive outcomes. Conclusions The observed changes in sedentary time and MVPA over time are promising for child health. Nevertheless, no meaningful associations with cognitive outcomes were found. Future studies with larger sample sizes should investigate whether specific types of activities that children engage in are associated with cognitive development overtime. Overall, this body of evidence could help inform future updates of guidelines concerning patterns of activity and health in the early years.