Playing Violent Video Games Reduces Agressive And Bullying Behavior In Vulnerable Teens

From "Video games do not make vulnerable teens more violent" on ScienceBlog:

Do violent video games such as ‘Mortal Kombat,’ ‘Halo’ and ‘Grand Theft Auto’ trigger teenagers with symptoms of depression or attention deficit disorder to become aggressive bullies or delinquents?

No, according to Christopher Ferguson of Stetson University and independent researcher Cheryl Olson from the US in a study published in Springer’s Journal of Youth and Adolescence. On the contrary, the researchers found that the playing of such games actually had a very slight calming effect on youths with attention deficit symptoms and helped to reduce their aggressive and bullying behavior.
Ferguson and Olson studied 377 American children, on average 13 years of age, from various ethnic groups who had clinically elevated attention deficit or depressive symptoms. The children were part of an existing large federally funded project that examines the effect of video game violence on youths.***Regarding concerns about some young mass homicide perpetrators having played violent video games, Ferguson stated, "Statistically speaking it would actually be more unusual if a youth delinquent or shooter did not play violent video games, given that the majority of youth and young men play such games at least occasionally."