Wednesday, August 02, 2006

Study Links Military Duty in Iraq to Lapse in Some Mental Ability

A large study of Army troops found that soldiers recently returned from duty in Iraq were highly likely to show subtle lapses in memory and in ability to focus, a deficit that often persisted for more than two months after they arrived home, researchers are reporting today.

But the returning veterans also demonstrated significantly faster reaction times than soldiers who had not been deployed, suggesting that some mental abilities had improved.

The slight deficit, often unnoticed by the soldiers, could make it difficult for some of them to learn and remember information as quickly as they are accustomed to, the authors said. These lapses are more common but less disabling than emotional reactions to combat like depression or post-traumatic stress disorder, the researchers said, and in many cases probably reflect a natural adaptation to life in Iraq, with the reaction time strengthening at the expense of some other mental functions.

“We’re talking about a level of change that is not alarming and shouldn’t send people running to the doctor, but changes that some may notice when they are trying to perform in very demanding contexts” like a challenging civilian job, said the lead researcher, Jennifer J. Vasterling of the Southeast Louisiana Veterans Health Care System and Tulane University.

The study, appearing in The Journal of the American Medical Association, is the first to track carefully such changes in mental functioning over time in soldiers who deployed to a war zone and those who did not.

Researchers tried to measure similar changes in troops after the Persian Gulf war of 1991. Many of those veterans, reporting chronic problems with concentration, suspected that they had been exposed to toxic gases that might have been a cause. But investigators had too little information about them from before they went to war to make meaningful comparisons.

Dr. Andy Morgan, a psychiatrist at Yale, said the new findings, when further tracked over time, could help doctors predict which soldiers will adapt quickly to civilian life and which will have chronic problems adjusting. “This kind of data should help us find early markers of trouble,” Dr. Morgan said, “and help us learn how to intervene if someone is headed for pathology.”

The research team led by Dr. Vasterling administered a battery of mental tests to 654 male and female soldiers who served in Iraq at various times from April 2003 to May 2005. The tests, more than 20 in all, were given before and after deployment, and included one in which participants had to pay close attention to a computer screen as letters flashed by, waiting to flag each F they saw. In another test, they were asked to memorize simple diagrams and try to recreate them 30 minutes later.

The soldiers did significantly worse in tasks that measured spatial memory, verbal memory and their ability to focus than did 307 soldiers who had not been deployed to Iraq.

But the returning soldiers scored about the same as their peers on most of the other tests. And they outperformed those who had not been deployed in a test of reaction time, measured in the fraction of a second it takes to spot a computer icon and react. This finding in itself suggests that the soldiers’ minds had adapted to the dangerous, snap-judgment conditions of war, experts said.

The deficits the soldiers showed “are perhaps better considered as essentially normal coping experiences,” Matthew Hotopf of King’s College London and Simon Wessely of the King’s Centre for Military Health Research, also of London, wrote in an editorial accompanying the article.

In effect, the brain, like the rest of the body, builds the muscles it most uses, sometimes at the expense of other abilities, say psychologists who study short-term memory and concentration. If reaction time is more critical to survival than verbal memory, the brain will devote its limited resources to that mental quickness.

Living for months at a time on adrenaline also affects brain function, soldiers and psychiatrists say. In a coming paper, Dr. Morgan and a team of other researchers found that elite soldiers under intense stress performed no better than pre-teenage children in tests of spatial memory. They recovered their abilities when the threat had subsided.

“We think this prefrontal brain area involved in organization and complex spatial memory is knocked out temporarily by high levels of adrenaline,” Dr. Morgan said.

NYT

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