Abstract Background Tetris has been proposed as a preventive intervention to reduce intrusive memories of a traumatic event. However, no neuroimaging study has assessed Tetris in patients with existing posttraumatic stress disorder (PTSD) or explored how playing Tetris may affect brain structure.Methods We recruited patients with combat-related PTSD before psychotherapy and randomly assigned them to an experimental Tetris and therapy group (n = 20) or to a therapy-only control group (n = 20). In...