By Steven Reinberg
TUESDAY, Sept. 4 (HealthDay News) -- Exposure to combat stress can have subtle, long-lasting effects on brain wiring, although most war-related brain changes clear up with time, a small Dutch study found.
Researchers evaluating 33 healthy soldiers just back from deployment in Afghanistan found that problems with concentration during complex thinking tasks were common early on, but eventually improved.
But, subtle changes involving brain circuitry appeared longer-lasting.
"Almost a quarter of soldiers coming back from Iraq and Afghanistan experience some difficulty in social and operational functioning," said lead researcher Guido van Wingen, from the Brain Imaging Center at the University of Amsterdam.
"What we wanted to know is how that could be related to brain function," he said.
For the study, published online Sept. 3 in Proceedings of the National Academy of Sciences, van Wingen's team looked at members of the NATO International Security Assistance Force peacekeeping operation, before and six weeks after a four-month deployment in Afghanistan.
The investigators compared these soldiers with 26 soldiers who were never deployed. A year and a half later, they followed up.
Using neuropsychological tests and functional MRI, the researchers did identify changes in brain function, specifically in the midbrain, van Wingen said.
The prolonged stress of armed combat, enemy fire and explosions initially interfered with the ability to concentrate during complicated tasks, but after 18 months the ability to sustain attention returned, the study found.
"The brain rapidly adapted to the situation in Afghanistan, but changes back when it returns to a safe environment," van Wingen said. "This shows how plastic the brain is and that's reassuring to know."
However, changes to the connections between the midbrain and the prefrontal cortex persisted at the 18-month follow-up, suggesting combat stress might have long-lasting effects on brain wiring, the researchers added. How these changes might affect people long-term isn't known, van Wingen noted.
It's possible that the long-term changes in connectivity could make the soldiers vulnerable to future stressors, which could in turn affect their social lives and employment, the researchers said.
Simon Rego, director of psychology training at Montefiore Medical Center/Albert Einstein College of Medicine in New York City, said the study is valuable.
"This study is important because while it is clear that prolonged stress increases the risk of psychiatric symptoms like PTSD symptoms, and negatively impacts mental functioning -- problems with sustained attention and memory -- it has been unclear whether these deficits are a cause or consequence of one another, or are caused by the stress itself, a preexisting neural abnormality, or some combination of these factors," said Rego.
While these researchers found combat stress had a negative impact on sustained attention due to functional and structural changes in the brain, the good news is that at the long-term follow-up they found that the brain areas of these soldiers had largely recovered from the adverse effects of stress, Rego said.
This suggests that the human brain can largely overcome the damage caused by prolonged stress, he said.
"Unfortunately, the bad news is that the way certain parts of the brain interacted with other parts of the brain did not show the same recovery," Rego said.
"This may make these individuals more vulnerable to stressors they face in the future, which in turn may ultimately play a role in the development of psychiatric symptoms -- as opposed to being a consequence of them," he added.
For more information on stress, visit the U.S. National Library of Medicine.
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