Combat Stress Affects Soldiers' Cognitive Function
Some functional and structural brain changes reversible, but others persist over the long term
WEDNESDAY, Sept. 5 (HealthDay News) -- Combat stress has adverse effects on the mesofrontal circuit of the brain that are partially reversible, according to research published online Sept. 3 in the Proceedings of the National Academy of Sciences.
To examine the long-term effects of prolonged stress, Guido A. van Wingen, Ph.D., of Radboud University in Nijmegen, Netherlands, and colleagues evaluated 33 soldiers who had a four-month deployment to a combat zone; the soldiers were assessed before and 1.5 months and 1.5 years after returning from their mission. Questionnaires were used to assess stress, and neuropsychological tests, diffusion tensor imaging, and functional magnetic resonance imaging were conducted. The results were compared with those from a group of 26 healthy soldiers who had never been deployed. Nine participants in each group did not complete long-term follow-up.
The researchers identified reduced midbrain activity and integrity in the soldiers who had experienced combat stress, which correlated with compromised sustained attention. After 1.5 years, these functional and structural changes had normalized. Soldiers exposed to combat stress had a persistent reduction in functional connectivity between the midbrain and prefrontal cortex, which persisted at long-term follow-up.
"In conclusion, our results demonstrate that combat stress affects the midbrain and thereby compromises sustained attention. These consequences of combat stress were reversible," the authors write. "However, the persistent changes in mesofrontal connectivity may increase the vulnerability to subsequent stressors and promote later development of difficulties with cognitive, social, and occupational functioning."