Researchers from Tel Aviv University have located risk factors for post-traumatic stress disorder. The risk factors include both behavioral and genetic markers that raise the risk of PTSD during military service. The research is a joint project of the U.S. National Institute of Mental Health and the Israel Defense Forces' mental health branch. Based on the results, the researchers are developing an attention bias modification treatment program for combat soldiers to reduce the chances of PTSD during battle.
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Some 20 percent of soldiers will develop clinical signs of PTSD at some point after being exposed to conditions of heavy fighting, medical literature shows. PTSD is popularly known as shell shock, and symptoms often include flashbacks, nightmares and severe anxiety, as well as uncontrollable thoughts about the traumatic events. PTSD can also involve avoidance of stimuli associated with the trauma and increased arousal, causing difficulties falling or staying asleep, rage and hypertension. The formal diagnostic criteria require that the symptoms last more than one month and cause significant impairment in social, occupational or other important parts of life.
The study is part of Ilan Wald's doctoral research, and was supervised by Yair Bar-Haim, professor of psychology and neuroscience and head of the School of Psychological Sciences at Tel Aviv University, and eight other researchers. The study examined 722 male IDF soldiers over the 2008-2010 period. All the soldiers were drafted for combat roles in the infantry and were intended to serve in the West Bank or Gaza. Of these, 405 soldiers were posted in areas where friction with Palestinian civilians was high, such as in Nablus, the casbah in Hebron and the Kisufim crossing point into Gaza. The other 317 soldiers were posted to quieter areas in the territories.
The researchers examined the soldier subjects both before and after their combat experiences, which they say is a first for studies of PTSD. They used various computer tasks and interviews to evaluate the soldiers. The soldiers underwent the first examination during basic training about two weeks after being drafted. Another examination took place about six months after enlistment and before going into combat duty, and the third examination came after six months of being in the field.
After six months of duty, 6 percent of the soldiers showed signs of PTSD. These numbers broke down into 8.1 percent of those in the high friction areas, and 5.1 percent of those in the quieter areas.
Many of the soldiers in the study were exposed to situations that may lead to PTSD: 23.2 percent were in places where rocks were thrown or weapons were present; 22.7 percent knew someone who was seriously injured or killed; 19.2 percent arrested wanted suspects; 10.6 percent searched homes; 7.9 percent fired or aimed their weapons at the enemy; 6.9 percent saw Israelis injured seriously or killed; and 4.8 percent saw ill women or children they could not help during their service. Soldiers saw two combat incidents on average during the study.
The key psychological test for the soldiers was intended to measure how they allocate their attention, by means of examining how much their attention was drawn to threats appearing on a computer screen. The study showed soldiers two words on the screen, one threatening and one neutral. Later the researchers measured the reactions of the soldiers to red dots that appeared where the words had been, and measured their response times. There were shorter response times to the dot that appeared after the word that attracted the soldier's attention earlier, said Bar-Haim. He explained that when soldiers go into action, their attention is strongly directed at threats, and those who do not turn their attention to the threats are the most likely to contract PTSD.
The findings showed that soldiers who ignored threatening words before and during their combat period were at a greater risk of PTSD. The researchers also collected saliva samples from the soldiers for genetic testing. They discovered that a specific gene, HTTLPR-5, which is connected to the neurotransmitter serotonin in the brain, affects the soldiers' chances of PTSD. The least effective version of the gene is 50 percent less effective in regulating serotonin in the brain compared to another genetic version - and the first version is the one that protected the soldiers the best from PTSD.
Based on their research, the scientists began to develop special computer programs to help combat soldiers at high risk for PTSD to practice directing their attention. This work is being conducted by the IDF's Medical Corps and is being funded by the U.S. military, and the results are due in a year and a half. Bar-Haim is also participating in other research with the U.S. military studying American soldiers who spent 11 months in Afghanistan in a attempt to examine their adaptation to normal life in American society after their return home.
Bar-Haim said the study was unique in that it is prospective - it examined the soldiers before they were even exposed to the experience of battle, and continued during their military service. Previous studies that tried to track risk factors for PTSD focused mostly on those who developed the disorder, and had a difficult time isolating the symptoms from previously existing problems the soldiers had that worsened during their service.
The research will be published in the JAMA Psychiatry of the Journal of the American Medical Association.