Children who spend more time on mobile phones, TVs, and video games may face a higher risk of developing attention problems as they grow, according to a first-of-its kind, large-scale study.

The findings, recently published in Translational Psychiatry [October 2025], indicate a link between longer screen time and more severe symptoms of attention-deficit/hyperactivity disorder (ADHD). Researchers from the University of Fukui in Japan also found measurable, though subtle, brain abnormalities among heavy screen users. 

“These findings suggest that screen time is associated with ADHD symptoms and brain structure, as well as their development,” they said.

Specifically:

• Longer screen time at ages 9–10 predicted higher ADHD symptoms two years later, after accounting for how severe the children’s symptoms were at the start.
• Higher screen time was linked to a smaller cortex, the outer layer of the brain responsible for higher-level thinking and attention, which in turn was linked to more severe ADHD symptoms. 
• Children with more screen time at the outset had a smaller right putamen, a region involved in language learning, addiction, and reward processing.
• Heavier screen use after two years was tied to slightly thinner development in three other cortical regions that support important cognitive functions, such as attention, working memory, and language processing.

Screen use has increased worldwide among children and adolescents, with more than one-third of U.S. parents of a child under 12 reporting their children began interacting with a smartphone before the age of 5, according to Pew Research. While digital devices are promoted as essential tools for school and social connection, their excessive use has been tied to disrupted sleep, reduced physical activity and negative impacts on mental health, behavior, and brain development.

This latest study is the first long-term look at how digital habits, attention, and brain development may interconnect during critical childhood years, the researchers say. They used data from the Adolescent Brain Cognitive Development (ABCD) study, a nationwide project that tracks nearly 12,000 children recruited at ages 9 and 10. 

Of those, they focused on children who had complete information about screen time, ADHD symptoms, and MRI scans. That included 10,116 children at baseline and then 7,880 at the two-year follow-up.

Children self-reported their time on various devices, including playing video games and watching television, and the research team calculated a weighted weekly average to reflect differences between weekday and weekend use. The study database did not include information about screen size.

Meanwhile, parents provided ADHD-related symptom ratings using the Child Behavior Checklist, and teachers submitted additional attention problem ratings for a smaller group of participants.

The study does not itself prove that screen time directly causes ADHD symptoms or changes in the brain, say the authors. Many factors influence those symptoms, and the differences observed were modest. More research is also needed, they say, to establish whether cortex size plays a role in the potential connection between screen time and attention problems.

Future research should test other measures of brain development, including how brain regions communicate and signals travel, they say.

Reference

Shou Q, Yamashita M, Mizuno Y. Association of screen time with attention-deficit/hyperactivity disorder symptoms and their development: the mediating role of brain structure. Translational Psychiatry. 2025;15(1). doi:10.1038/s41398-025-03672-1