Playing Tetris could be a treatment for Post Traumatic Stress Disorder (PTSD), an Oxford University study suggests.

PTSD is an anxiety disorder that develops after a person is exposed to psychological trauma. Flashbacks or unwanted memories from the trauma are a hallmark of PTSD. These involuntary memories can lend to a crippling inability to cope with the trauma. According to a Time report, 20 percent of U.S. veterans claim to have PTSD.

In the study, participants with no history of mental illness watched 20 minutes of traumatic footage involving injury or death. They were then divided into three groups. Thirty minutes after the film, one group sat quietly, one group played Tetris, and another group played a different trivia-based video game called Pub Quiz for 10 minutes each.

Participants who played Tetris had fewer flashbacks than the other two groups. In the 10-minute period, those who played Tetris had an average of four flashbacks, while those who played Pub Quiz had about six and those who did nothing experienced an average of 12.

"Engaging in a visuospatial task such as Tetris may offer a 'cognitive vaccine' against the development of PTSD flashbacks after exposure to traumatic events," the study said.

The "protective effect" of Tetris continued into the following week, when participants were asked to keep a journal of their flashbacks. The group that played Pub Quiz actually recorded the highest incidence of flashbacks, probably because the language and trivia skills required for the game use a different part of the brain, the study said.

"The current data also suggest that some computer games, such as the verbal game Pub Quiz, are unlikely to have a beneficial effect post-trauma, and may even have harmful effects on flashbacks when played soon after," the study concluded.

The same experiment was performed with a four-hour interval between the film and the task, and similar results were recorded. However, the experiment requires significantly more testing before Tetris or a similar task could actually be prescibed as a treatment for PTSD.