Objective The present study examined the impact of deployment on neuropsychological functioning and mood in Army National Guard personnel. We hypothesized that deployment on a peacekeeping mission, compared to non-deployment, would result in reduced proficiencies in neuropsychological performance and negative mood changes, and that such changes would relate to working in a high-strain job (high demands/low control), in accordance with Karasek’s demand-control model.

Methods This prospective cohort study involved 119 male soldiers (67 participants examined before and after deployment to the Bosnia operational theatre and 52 non-deployed soldiers assessed twice over a comparable period).

Results Unit-level adjusted, multivariate analyses found that deployed soldiers, compared to their non-deployed counterparts, demonstrated reduced proficiency in tasks involving motor speed [unstandardized coefficient B= -3.88, 95% confidence interval (95% CI) -6.38– -1.39; B= -3.84, 95% CI -5.55– -2.14; dominant and non-dominant hand, respectively] and sustained attention (B=0.031, 95% CI 0.009–0.054), along with decreased vigor (B= -2.71, 95% CI -3.63– -1.77). Deployed soldiers also showed improved proficiency in a working-memory task (B= -0.098, 95% CI -0.136– -0.060) with less depression symptomatology (B= -3.19, 95% CI -5.26– -1.13). Work stress levels increased over time in both deployed and non-deployed groups, but observed deployment effects remained significant after accounting for a high-strain job.

Conclusion The observed change in performance associated with peacekeeping deployment compared to non-deployment (slowed processing speed, reduced motor speed and reported vigor, together with improved proficiency in a working memory task) suggests an adaptive response to mission occupational stressors. This pattern does not appear to be influenced by working in a high-strain job. Further study is required to examine whether these results reflect transient or permanent changes in functioning.

Key terms assessment; deployment; military; mood; neurobehavior; neuropsychological functioning; peacekeeper; peacekeeping; US Army National Guard