Higher screen time linked to ADHD symptoms and altered brain development

Children aged nine to 10 with longer screen time show more ADHD symptoms and altered brain development two years on, new research has revealed.

A large US study of nearly 12,000 children reports what it says is the first developmental evidence that heavy screen use is linked to ADHD symptoms and structural brain changes.

The research followed 11,878 children aged nine to 10 over two years, using brain imaging and behavioural assessments to examine how daily screen exposure affects neurological development.

Scientists from the University of Fukui in Japan, led by assistant professor Qiulu Shou, assistant professor Masatoshi Yamashita and associate professor Yoshifumi Mizuno, analysed data from the Adolescent Brain Cognitive Development study.

The team found that longer daily screen time at the start of the study significantly predicted increased ADHD symptoms two years later, even after accounting for initial symptom levels.

Dr Yamashita said: “This study is the first to examine the relationship between screen time, ADHD symptoms, and brain structure from a developmental perspective using such a large-scale database.

“The findings indicate that excessive screen exposure may contribute to delayed brain maturation patterns commonly seen in children with ADHD.

“Our work provided some evidence toward growing concern about the association between digital media exposure and children’s mental and cognitive health.

“The results provide some neuroscientific evidences for the need to control screen time.”

Brain scans revealed that higher screen time was associated with a smaller cortex (the brain’s outer layer responsible for higher level thinking) and reduced volume in the right putamen, a region involved in language learning, addiction and reward processing.

After two years, excessive screen use was linked to hindered development of cortical thickness (a measure related to brain maturation) in areas important for cognitive function, including the right temporal pole and parts of the left frontal gyrus.

The research suggests that total cortical volume partially mediates the relationship between screen time and ADHD symptoms at baseline.

This means the observed link between longer screen exposure and greater symptom severity can be partly explained by the smaller cortical volume found in children with higher screen use.

Previous research had established correlations between screen time and behavioural issues, but most studies were cross-sectional, providing only a single snapshot rather than tracking changes over time.

This longitudinal approach allowed researchers to observe how screen habits influence brain development and symptom progression.

Dr Mizuno said: “Our findings provide evidence that longer screen time is associated with increased ADHD symptoms and brain structural development.

“The findings of our research enhance our understanding of the link between screen time and ADHD symptoms, as well as the neural mechanisms underlying ADHD.”