Negative affect predicts posttraumatic stress symptoms in Brazilian volunteer United Nations peacekeepers in Haiti.

Our study evaluated the relationship between positive affect (PA) and negative affect (NA) traits on the development of posttraumatic stress symptoms (PTSS) among peacekeepers. A longitudinal study with 138 army personnel deployed to a peacekeeping mission in Haiti was conducted. An instrument for measuring PA and NA traits was used before deployment. PTSS, indexed by posttraumatic stress disorder Checklist--Military Version (PCL-M) and frequency of stressful situations were measured after return. Regression analysis showed that both NA and number of stressful situations contributed toward increasing PCL-M scores (Adjusted R = 0.25; p < 0.001). We also found that NA traits interact with intensively stressful situations enhancing the occurrence of PTSS (Adjusted R = 0.32; p < 0.001). These findings suggest that NA traits are an important predictor for PTSS among peacekeepers and also worsen the consequences of being exposed to stressful situations.