Long-term study links childhood screen time to slightly better cognitive skills in teenagers

A study tracking the physical habits of children into adolescence has found that higher levels of screen time and less unsupervised physical activity are linked to better cognitive performance in teenagers. The research, published in Pediatric Exercise Science, reveals surprising relationships between daily movement and brain development.

Cognitive abilities under consideration include working memory, attention, and psychomotor speed. Cognitive development is particularly sensitive during childhood and adolescence. Studies have produced mixed results on how these changing habits affect the developing brain. Some suggest physical activity enhances cognition through increased blood flow and beneficial brain chemicals, while others find no link.

Physiological health factors, such as stiffer arteries, have also been associated with weaker working memory in teens. To understand the impact of long-term, cumulative exposure to both physical activity and sedentary time, researchers analyzed data from the Finnish Physical Activity and Nutrition in Children study, following 260 adolescents who were initially assessed between ages 6 and 9.

Over eight years, participants underwent assessments at baseline, two years, and eight years. Data was gathered from self-reported questionnaires and wearable fitness devices to measure various physical behaviors. At the final eight-year follow-up, when the adolescents were around 15 to 17 years old, they completed a computerized cognitive test battery evaluating reaction times, attention, working memory, and associative learning.

Self-reported data showed that increased unsupervised physical activity was associated with poorer working memory accuracy in adolescence. The researchers caution that this link may be influenced by factors such as sleep or homework. Conversely, more reported screen time was linked to faster reaction times and better overall cognitive scores.

The objective data from the fitness monitors showed a different pattern, suggesting that cumulative exposure to physical activity and sedentary time may have contrasting effects on cognitive abilities.