University of Fukui study links children's screen time to ADHD symptoms and brain structure

On November 20, a research group from the Research Center for Child Mental Development at the University of Fukui — comprising Assistant Professor Qiulu Shou, Assistant Professor Masatoshi Yamashita, and Associate Professor Yoshifumi Mizuno — announced that they had identified a link between children's screen time (time spent using television, video games, smartphones, etc.), the development of attention-deficit/hyperactivity disorder (ADHD) symptoms, and brain structure. These findings were obtained through analysis using data from the largest pediatric cross-sectional study in the United States. Children with longer screen time tended to score higher on ADHD symptoms measured two years later, and associations with brain structure were also observed. The results are expected to contribute to the development of healthy digital media usage guidelines during developmental stages. The results were published in Translational Psychiatry on October 31.

With the spread of the internet and digital devices such as smartphones, screen time among adolescents has been increasing rapidly. Excessive screen usage has been associated with reduced physical activity and sleep duration, as well as negative effects on mental health and academic performance, and impacts on brain development.

Previous studies had reported that screen time is associated with ADHD symptom severity, but most were cross-sectional studies examining a single point in time. This left developmental changes and neurological mechanisms poorly understood. Research on the relationship with brain structure using large-scale data to examine changes and causal relationships in specific regions such as the prefrontal cortex has also been limited.

The research group therefore used data from the "Adolescent Brain Cognitive Development (ABCD) Study," the world's largest pediatric longitudinal study led by the American National Institutes of Health (NIH). Utilizing this data, they conducted a detailed analysis of the relationships between three factors: screen time, ADHD symptoms, and brain structure.

The study included approximately 10,000 children aged 9-10 years at baseline and 7,880 children for whom follow-up data was obtained two years later. MRI imaging data, behavioral data, and screen time data were used in the analysis.

The study examined the effects of baseline screen time on ADHD symptoms and changes in brain structure two years later, as well as whether brain structure mediates the relationship between screen time and ADHD symptoms.

The results showed that screen time was significantly associated with increased ADHD symptoms. It was also associated with reduced cortical thickness in brain regions including the right temporal pole, left superior frontal gyrus, and left rostral middle frontal gyrus. Furthermore, total cortical volume was found to partially mediate the relationship between screen time and ADHD symptoms.

The structural brain changes involving reduced cortical volume and their potential association with attention control difficulties and impulsivity seen in ADHD symptoms are considered clinically significant.

Journal Information
Publication: Translational Psychiatry
Title: Association of screen time with attention-deficit/hyperactivity disorder symptoms and their development: the mediating role of brain structure
DOI: 10.1038/s41398-025-03672-1