Background: As Canada's mission in Afghanistan winds down, the Canadian Forces (CF) are reflecting on the psychological impact of the mission on more than 40,000 deployed personnel.
Methods: All major CF studies of mental health outcomes done before and during the Afghanistan era are summarized, with an eye toward getting the most complete picture of the mental health impact of the mission. Studies on traumatic brain injury (TBI), high-risk drinking, and suicidality are included given their conceptual link to mental health.
Results: CF studies on the mental health impact of pre-Afghanistan deployments are few, and they have inadequate detail on deployment experiences. Afghanistan era findings confirm service-related mental health problems (MHPs) in an important minority. The findings of the studies cohere, both as a group and in the context of data from our Allies. Combat exposure is the most important driver of deployment-related MHPs, but meaningful rates will be found in those in low-threat areas. Reserve service and cumulative effects of multiple deployments are not major risk factors in the CF. Many deployed personnel will seek care, but further efforts to decrease the delay are needed. Only a fraction of the overall burden of mental illness is likely deployment attributable. Deployment-related mental disorders do not translate into an overall increase in in-service suicidal behavior in the CF, but there is concerning evidence of increased suicide risk after release. TBI occurred in a distinct minority on this deployment, but severe forms were rare. Most TBI cases do not have persistent "post-concussive" symptoms; such symptoms are closely associated with MHPs.
Conclusion: The mental health impact of the mission in Afghanistan is commensurate with its difficult nature. While ongoing and planned studies will provide additional detail on its impacts, greater research attention is needed on preventive and therapeutic interventions.
Keywords: Canada; Military personnel; combat; epidemiology; post-traumatic; stress disorders.