I recently read an article in the Phildelphia Inquirer that said there are mixed conclusions about video games and their effects on the people who play them for many years. You may be surprised that hundreds of studies on the link between violent video games and aggressive behavior have shown not that these games cause children to become violent themselves, but that aggressive people like playing aggressive video games.
A study from Yale University released in November 2010 suggests that most teens who play video games do not develop unhealthy behaviors, but a small minority of teens who play video games and already have addicitve traits may be more likely to smoke, use drugs, fight or become depressed.
The same study found that the boys who played video games (about 76% of male respondents) typically earned a higher grade average, were less likely to smoke and were more likely to say they'd never used alcohol or marijuana. Among girls, just 29% of those surveyed said they played video games, and those that did were more likely than the girls who didn't play video games to get into serious fights or carry weapons to school. These findings were interpreted to mean that for boys, playing video games is normal but for girls who play - they tend to be more aggressive.
Other research suggested that playing video games is socially isolating, but different studies showed that almost 60% of frequent gamers play with friends or siblings. In any case, if your child spends most of their time sitting on the couch, staring at a screen rather than running around outside, playing sports or engaging in an educational activity, you have rightful cause for concern.