Brain structure changes may partially explain the link between screen time and ADHD

An analysis of the Adolescent Brain Cognitive Development (ABCD) study data found that children 9–10 years of age who spent more time using screens tended to have slightly more severe ADHD symptoms. They also tended to have slightly reduced cortical thickness in specific brain regions. The paper was published in Translational Psychiatry.

Screen time refers to the amount of time a person spends using devices with screens, such as smartphones, tablets, computers, and televisions. It includes both active engagement, like gaming, and passive viewing, like watching videos.

In recent years, children have been exposed to screens at increasingly younger ages due to the widespread availability of mobile devices in homes. Many studies show that overall daily screen time has risen steadily among children, especially during and after the COVID-19 pandemic when online schooling and digital entertainment expanded. Younger children tend to use screens mainly for cartoons and simple games, while older children use them for social media, schoolwork, and more complex games.

Research indicates that excessive screen time is linked with shorter sleep duration, increased sedentary behavior, and reduced outdoor play. Some findings also suggest associations with attention problems and emotional difficulties, although these effects are influenced by family context and the type of content being consumed. Educational screen use, such as interactive learning apps or supervised school tasks, tends to have fewer negative effects than passive entertainment.

Parents increasingly report struggling to set limits because devices are integrated into daily routines and children resist restrictions. Trends also show that many children multitask across multiple screens, such as watching videos while gaming or chatting with friends. Health organizations generally recommend limiting recreational screen time and encouraging balanced routines that include physical activity and social interaction.

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Study author Qiulu Shou and her colleagues noted that previous studies indicate that children spending more time using screens tend to show more severe symptoms of attention-deficit/hyperactivity disorder (ADHD). ADHD is a neurodevelopmental disorder characterized by age-inappropriate inattention or hyperactivity/impulsivity.

They wanted to verify these findings and explore potential neural mechanisms behind the links. The researchers noted that ADHD symptomatology has been previously associated with delayed cortical maturation and alterations in cortical thickness.

They analyzed data from the Adolescent Brain Cognitive Development (ABCD) study. This is a longitudinal database comprising 11,878 children from the U.S., aged 9–10 years at the start of the study. Data from 10,116 children at the start of the study were used in the analysis. For 7,880 of these children, data from two years later were also available and included in the analysis.

Screen time was assessed using a self-report questionnaire and calculated as the total time spent using various devices, including playing video games and watching TV. ADHD symptoms were reported by parents using the Child Behavior Checklist and by teachers using the Brief Problem Monitor. Participating children underwent magnetic resonance imaging (MRI), providing researchers with information about the structure of their brains.

Results showed that children spending more time using screens were significantly associated with more severe ADHD symptoms, although the magnitude of the association was small. Higher screen time was also linked to reduced cortical thickness development in specific regions of the brain over the two-year period. These regions were the right temporal pole, left superior frontal gyrus, and left rostral middle frontal gyrus.

The study authors tested a statistical model proposing that cortical volume partially mediates the relationship between screen time and ADHD (i.e., that screen time leads to reduced cortical volume, which, in turn, leads to more severe ADHD symptoms) and found evidence supporting this model.

“These findings suggest that screen time is associated with ADHD symptoms and brain structure, as well as their development, potentially providing insights into the neural mechanisms underlying the association between screen time and ADHD symptomatology,” the study authors concluded.

The study contributes to the scientific understanding of the neural underpinnings of ADHD. However, it should be noted that the associations reported in this study are weak. They were detectable largely because the study was conducted on a massive group of children. The associations were small at the start of the study and remained small regarding ADHD symptom development two years later. In other words, while the results showed that screen time is statistically associated with ADHD symptoms and their development, the effect sizes suggest the clinical impact may be marginal.

The paper, “Association of screen time with attention-deficit/hyperactivity disorder symptoms and their development: the mediating role of brain structure,” was authored by Qiulu Shou, Masatoshi Yamashita, and Yoshifumi Mizuno.