Playing violent video games produces changes in areas of the brain that help control emotion for at least a week, new research suggests.

Researchers reported their findings this week at the annual meeting of the Radiological Society of North America.

For the study, Dr. Yang Wang, a radiologist at the Indiana University School of Medicine in Indianapolis, led a team who recruited divided 22 healthy men who were between 18 and 29 years old and not regular players of violent games.

They divided them randomly into two groups: one group was asked to play a shoot-em-up style video game for 10 hours over the course of a week and then to refrain from playing the game for a second week. The second group was instructed not to play any violent video games at all over the two weeks.

All of the study subjects underwent functional magnetic resonance imaging tests at the beginning of the study, after one week and at the end of the study.

At one week, the game players had less activation in parts of the brain associated with emotional control than they had at baseline than the control group. To test this, during the fMRI, the men completed an "emotional interference task," pressing buttons according to the colour of visually presented words. Words indicating violent actions were interspersed among nonviolent action words.

The video game group members showed less activation in the left inferior frontal lobe during the emotional task compared to both their baseline results and compared to the control group.

They also had less activation in a brain area that controls cognitive function -- the anterior cingulate cortex -- during a counting task.

Activation increased again after the second week, when the men didn't play the game.

"These findings indicate that violent video game play has a long-term effect on brain functioning," Dr. Wang concluded.

The researchers did not look at how these brain changes might affect real-world behaviour.

But Wang's colleague and study co-author Dr. Vincent P. Mathews says young adults should be concerned about the effects of these games.

"I think a lot of gamers would like to believe that these games have no effects on their brains, but I think our results show that they do and so I think they need to be concerned about that," he told CTV News.

"If they are going to make the choice to play video games, they need to be aware that they are going to have these changes in brain function and potentially may have some changes in behaviour as well," he said.

The study has not been published or subjected to peer review.