Childhood screen time may support cognitive processing in teenagers

In a recent Finnish study, more screen time since childhood was associated with better cognitive processing in adolescence. According to one of the researchers, we should not regard screen time solely as harmful. The most important thing is to find a balance between physical activity and screen time that promotes active thinking.

Adolescents' scarce physical activity is a major challenge in terms of public health. Sedentary lifestyle has been shown to decrease school achievement, while physical activity is known to promote brain functions especially for adults. However, there is little research evidence about the connections of physical activity and sedentary time in childhood and adolescence with regard to cognitive processing in adolescence, although these life stages are pivotal for brain development. Various factors that influence cognitive processing in childhood and adolescence can be reflected far into adulthood also in terms of educational choices and working life. 

The study investigated how physical activity, sedentary behaviour and screen time from childhood to adolescence are associated with cognitive processing in adolescence and whether there are any sex differences in these connections. In addition, the researchers also examined the role of the intensity of physical activity in this respect.

Screen time can support thinking and learning

According to the findings, higher amount of screen time since childhood were connected to better cognitive processing in adolescence.

- The findings suggest that screen time can support children's and adolescents' cognitive processing. Presumably, the essential point here is what kind of things they do in their screen time. Teachers and parents should encourage children to use devices and screens in such ways that promote active thinking, problem-solving, creativity and learning, states Doctoral Researcher Petri Jalanko from the University of Jyväskylä.

- We should not regard screen time solely as harmful but seek balance between physical activity and screen time that promotes active thinking, Jalanko summarizes.

Physical activity and sedentary time associated in complex ways with cognitive processing

In girls, the higher amount of light-intensity physical activity since childhood was associated with better working memory in adolescence. In boys, then again, higher amount of guided physical activity from childhood to adolescence was associated with better working memory in adolescence.

Surprisingly, lesser self-reported unsupervised physical activity was connected to better cognitive processing in adolescence. Instead, physical activity or sedentary time as measured by a heart rate and movement sensor were not associated with cognitive processing. The differences may be explained by the fact that the heart rate and movement sensors cannot tell what a person is actually doing during the physical activity and sedentary periods.

- Our study indicates that the connections of physical activity and sedentary behaviour to cognitive processing are complex and depend on the sex, the type and assessment method of physical activity and sedentary time. Moreover, boys and girls may benefit from different types of physical activity in view of brain health, Jalanko adds.

-However, we need more intervention studies to find out causal relations and sex differences in this respect. Moreover, it is important to examine more specifically the effects of the intensity of physical activity on changes taking place in cognitive processing.

The findings are based on an eight-year follow-up of the PANIC study on children's physical activity and nutrition. The current study involved 124 girls and 136 boys, whose average age was 15.8 years. Physical activity and sedentary behaviour were measured by a device that combined heart rate and movement measurements and also by a survey questionnaire. Learning, attention and working memory were assessed by means of the CogState test battery. The research article is published in the Pediatric Exercise Science journal.