The study, which was based on a two-year survey of 3,034 children in Singapore, found that 9 percent of players were addicted, as defined by how much their playing interfered with their grades, emotions and relationships.
The researchers weren't entirely surprised by that result, because of similar studies in the United States and other countries. What shocked them was how the reduction of troublesome gaming habits corresponded with fewer depressive symptoms.
"When they dropped below the pathological line (for gaming addiction) their depression decreased, their anxiety decreased, their social phobia decreased," said Douglas Gentile, the lead author. "That's kind of the opposite of what we expected to find. We expected that maybe the gaming followed those other issues."
Gentile previously directed research at the Minneapolis-based National Institute for Media and the Family.
The authors of the study, which was published in the American journal Pediatrics, say the finding requires more research. They doubt a cause-effect relationship between gaming addiction and depression. More likely the disorders are related in some unknown way, they wrote.
Regardless, Gentile said the study upholds the concept of gaming addiction: "It's not just a symptom of other problems," he said. "It looks like a problem in its own right."
There is broad agreement that some children and even adults play video games for excessive periods of time. Minnesota Student Survey data for 2010 showed about one in 10 boys playing more than 21 hours of video games per week. (Interestingly, the data showed an overall decline since 2007 in children who play any video games, though the decline was eclipsed by an increase in texting and online activities.)
Whether excessive gaming equals addictive gaming is a matter of much dispute.
The Entertainment Software Association criticized the study and Gentile, an Iowa State University researcher who has published other papers on video game addiction. The trade group argued that Gentile used an unproven definition of pathological gaming and made negative interpretations of "trivial" differences between the behaviors of problem gamers and other children in the survey.
"This research is just more of the same questionable findings by the same author in his campaign against video games," said Richard Taylor, a senior vice president for the association.
The American Psychiatric Association has considered whether to add video game addictions to the fifth edition of its diagnostic manual. So far, its leaders haven't seen enough evidence to support inclusion, though that could change before publication in May 2013. The association also could make a statement in the new manual's appendix calling for more research on the subject.
A broader question is how much addictions can be caused by mere behaviors, such as gaming, rather than by substances such as alcohol or cocaine that alter brain chemistry. The psychiatric association is proposing to add only one behavioral addiction, pathological gambling, to its diagnostic manual, due to the depth of research on that topic. However, studies have suggested everything from shoplifting to pulling hair can be addictive.
Gentile's study said there are likely parallels between video gaming and gambling, both of which might cause addictions by stimulating the pleasure centers of the brain.
Gentile said his study was among the first to address a key question about video gaming: whether a childhood addiction would be temporary. Of the children deemed video game addicts at the start of the survey, 84 percent still met that threshold two years later. (The threshold was whether children reported five of 10 negative consequences related to gaming.)
One area of agreement for Gentile and the gaming industry is the need for parents to monitor their children's gaming activities and to step in if they become problematic. Gentile said his study found no evidence that any particular type of game presented more risk than another. It did find that children meeting the study's threshold for addiction trended toward more violent games over time.
"It's not that one game is more addictive, the way crack is more addictive than cocaine. It's more about impulse control," he said. "It's that you know you should do your homework but you can't stop playing."