A study of soldiers who took part in the ISAF mission in Afghanistan between 2008 and 2010 has found that their brains adapt when they are continuously exposed to stress. The perceived threat appears to be the major predictor of brain adaptation, rather than the actual events. In other words, if a roadside bomb goes off right in front of you, the degree to which you perceive this as threatening is what counts. This is what determines how the brain and the stress system adapt.
These results will be published in the journal Molecular Psychiatry on January 18.
Between 2008 and 2010 the researchers studied a group of 36 soldiers. Before and after taking part in the mission, the soldiers' brain activity was measured and compared with the brain activity of a control group of equal size who stayed at home. Unique to this study is that it is the first to use a control group. This control group, which stayed behind in the barracks in the Netherlands, had received similar combat training.
First study with control group
'Thanks to the design of our study, for the first time we can now conclude that the effects on the brain really are due to experiences in combat. The soldiers taking part in the ISAF mission in Afghanistan had their brains scanned twice. They also filled out questionnaires about their experiences during combat. The soldiers did not develop posttraumatic stress disorders (PTSD) but their experiences did have an effect on the neural circuits in the brain that regulate vigilance and that are also involved in controlling emotion. This effect persisted for at least two months after the soldiers returned home,' says Guido van Wingen of the Donders Institute for Brain, Cognition and Behaviour at Radboud University Nijmegen, first author of the study.
Military mental health study
This research is part of a long-term project in collaboration with the Military Mental Health Research Centre and the Rudolf Magnus Institute of Neuroscience in Utrecht. Activity in the amygdala and insula, the fear and vigilance centres in the brain, increases in all soldiers on mission. But the changes in the emotional control centre in the frontal lobe depend strongly on how they perceived threatening events during the mission. The researchers are now working on a follow-up study to see how long the changes in soldiers' heads remain, and whether or not those that perceived high levels of stress are also at higher risk of developing symptoms of posttraumatic stress.
- G A van Wingen, E Geuze, E Vermetten, G Fernández. Perceived threat predicts the neural sequelae of combat stress. Molecular Psychiatry, 2011; DOI: 10.1038/mp.2010.132
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