(CNN) -- When it comes to playing video games, it seems moderation is important to a child's mental health. A new study published by the American Academy of Pediatrics finds excessive gaming may lead to depression, anxiety, and poor grades in school.
Researchers in the U.S. and overseas looked at more than 3,000 elementary and middle-school children in Singapore and found that almost 9% of them were considered pathological or "addicted" to gaming -- similar percentages were found in other countries.
Over a two-year period about 84% of those who started out as excessive gamers remained so, indicating that this may not simply be a phase that children go through. Boys were more likely to show symptoms of excessive gaming. Overall those considered "pathological" gamers displayed higher levels of depression and other mental health issues than their peers who played fewer video games. The researchers also found that students who did stop their excessive gaming reduced their levels of depression, anxiety and social phobia.
There is debate in the medical community as to whether pathological or "addictive" video gaming should be listed as a mental disorder in the American Diagnostic and Statistic Manual of Mental Disorders -- a guide used by the American Psychiatric Association in diagnosing mental disorders.
To gauge the level of pathological gaming, the study authors asked students questions similar to the type used to diagnose gambling addiction such as: were students becoming more preoccupied with video games, did they lie about the amount of time spent playing, had their schoolwork suffered, and if playing helped them escape from problems or bad feelings.
A young person was labeled pathological or "addicted" if the practice caused problems in his or her life.
"And we define that as actual functioning -- their school, social, family, occupational, psychological functioning. To be considered pathological, gamers must be damaging multiple areas of their lives," explains study author Douglas Gentile, Ph.D., developmental psychologist at Iowa State University in Ames.
Pathological gamers were playing an average of more than 31 hours a week compared with their less excessive peers who played about 19 hours a week.
Gentile and the other researchers also looked at potential risk factors for becoming pathological gamers.
"Kids who were more impulsive were more likely to become addicted; they had a harder time managing their impulse control. If they were socially awkward then they were more likely to be addicted and if they spent a greater amount of time then the average kids playing games," explained Gentile.
The Entertainment Software Association disagreed with the findings. " "There simply is no concrete evidence that computer and video games cause harm," a statement from the organization said. "In fact, a wide body of research has shown the many ways games are being used to improve our lives through education, health and business applications."
Dr. Don Shifrin, spokesperson with the American Academy of Pediatrics, called Gentile's study important. "It allows us to take a harder look at how gamers play and whether there is balance in the lives of our children and teens," he said
The AAP recommends that elementary school age children engage in no more than one hour of screen time a day, and high schoolers no more than two.