It may take years or months to show up but according to a recent study at least nine percent of returning U.S. troops have experienced post-traumatic stress disorder (PTSD).
The study is published in the British Medical Journal and looks at PTSD among 50,000 men and women returning from Iraq and Afghanistan who have performed combat duty.
This is the latest and most complete accounting of what returning troops are experiencing though some say the numbers may be low.
Post-traumatic stress disorder (PTSD) is characterized by outbursts of anger, an inability to sleep and concentrate, an exaggerated response, hopelessness and reliving the event.
Researchers point to extended tours, a constant risk of roadside bombings, urban combat, watching a friend suffer being wounded or killed, as all contributors to the high stress levels.
The troops were questioned from 2001 to 2003. Then there were follow-ups again from 2004 to 2006.
Among those deployed who saw combat, but had never experienced PTSD previously, 8.7 percent report the symptoms of the severe stress disease. Compare that to non-combat personnel that report PTSD 2.1 percent of the time.
"The unpredictability and intensity of urban combat, constant risk of roadside bombs, multiple and prolonged tours, and complex problems of differentiating enemies from allies can leave many troops with high stress levels and possible lasting health consequences," the researchers wrote.
The study was conducted by the Department of Defense Center for Deployment Health Research at the Naval Health Research Center in San Diego.
Another study conducted by The Institute of Medicine, had indicated that about 12.6 percent of Iraq servicemen and women and 6.2 percent of those in Afghanistan have experienced PTSD.
Headlines across America talk about returning veterans who go ballistic.
One took an AK-47 assault rifle into a late night 7-11 wearing his combat uniform. The 20-year-old needed alcohol to sleep. Matthew Sepi allegedly killed who he perceived to be an enemy. He is facing murder charges.
The New York Times found 121 cases of veterans committing or being charged with killings after returning from the war. Alcohol abuse, family disruption, and mental instability all become part of the picture. Some turned on family members, some turned on other soldiers. Most of the veterans were still in the military.
The Department of Defense has held hearings on the high number of mental disorders among returning U.S. troops and finds suicide rates estimated to be about 5,000 every year, with some of those veterans under treatment at the Veterans Administration.
Critics say the Pentagon is not adequately staffed to handle the problem. #