Children who spend excessive hours watching television or playing video games are more prone to disorders affecting the brain such as attention deficit disorder, say US researchers.

Though the research has not discovered a biological basis for the effect of screen time on kids’ education, it suggests that watching TV programs or playing video games could make kids end up having trouble concentrating in school.

Children who spent more than two hours a day in front of screens were 67% more likely to have problems with paying attention compared to their peers, the study found. Watching TV for too long was also found to be linked to increased aggression and childhood weight gain, according to Douglas Gentile and other researchers.

The researchers followed about 1,300 children who were already of school age to understand how video games affected a child’s ability to concentrate. For a period of one year, the hours the childrent spent watching TV and playing games was recorded with the help of their parents.

The researchers also interviewed the children’s teachers about the children’s behavior in school. Their key point of query was to know if any of the children in the study group were prone to interrupt others or get distracted, in particular.

The children who watched TV excessively or played video games for a long period of time had slightly more problems concentrating on their school-related tasks, they concluded.

Children with extreme levels of attention difficulty are sometimes diagnosed with attention-deficit hyperactivity disorder (ADHD), and 3-7% of school-age children suffer from the condition.

A related study in college undergraduates also made a similar finding.

In the study, the researchers wanted to know how many college undergraduates were likely to have ADHD. More than two hours daily watching of TV screen also caused problems with attention in college undergraduates.

Although it would be difficult to find causal links at this stage, it was common sense that attention problems did not cause television watching, Gentile said.