Playing Tetris and Candy Crush may be more useful than for just passing the time. A study, published in Molecular Psychiatry, found playing these games after a traumatic event could block the intrusive memories of the event and possibly reduce the rates of depression and post-traumatic stress disorder.

Led by Lalitha Iyadurai of the University of Oxford in the United Kingdom and Emily Holmes of Karolinska Institutet in Sweden, the study explains how a brief intervention with these low-cost games may reduce intrusive memories of traumatic event in patients. These recollections—which bring back the sounds, sights and emotions of a traumatic event—are directly correlated with stress disorders, anxiety and depression. In clocking these memories, Iyadurai and Holmes hope the games can provide relief to patients in the time after their traumatic event.

The study asked 71 patients, who in the waiting room of the emergency department of an Oxford, U.K., after seeing or being involved in a car accident, to recall the accident then play Tetris for 20 minutes. All participants were given the game intervention within six hours of the accident and asked to report any intrusive memories over the next week.

The psychological intervention of playing Tetris resulted in a reduction in the number of intrusive memories by 62 percent in the following week, compared to patients who had not received the game. The Tetris group also experienced less distress from intrusive symptoms. Researchers believe that the intervention, which can be distributed upon entry and has no need for a specialist, can reduce the symptoms associated with a traumatic experience.

"A brief psychological intervention including Tetris offers a cognitive 'therapeutic vaccine' that could be administered soon after a traumatic event to prevent the recurrence of intrusive memories of trauma in the subsequent week," said Iyadurai.