Washington - Newly diagnosed cases of post-traumatic stress disorder among U.S. troops sent to Iraq and Afghanistan surged 46.4 percent in 2007, bringing the five-year total to nearly 40,000, according to U.S. military data released on Tuesday.

    The statistics, released by the Army, showed the number of new PTSD cases formally diagnosed at U.S. military facilities climbed to 13,981 last year from 9,549 in 2006.

    The numbers rose as President George W. Bush poured extra forces into Iraq to try to quell sectarian violence and extended Army tours from 12 to 15 months. The United States has also sent more forces to Afghanistan.

    The figures, encompassing all four branches of the U.S. armed services, showed that the Army alone had 10,049 new PTSD cases last year.

    This brings to 39,366 the number of PTSD cases diagnosed at military facilities between January 1, 2003, and December 31, 2007, among troops deployed to Iraq or Afghanistan.

    The totals include 28,365 cases for the Army, 5,641 for the Marines, 2,884 for the Navy and 2,476 for the Air Force.

    Army officials said the larger number of PTSD diagnoses in recent years partly reflects greater awareness and tracking of the disorder by the U.S. military.

    Longer, Multiple Combat Tours

    "But we're also exposing more people to combat," Lt. Gen. Eric Schoomaker, the Army surgeon general, told reporters.

    Experts also say PTSD symptoms increase as soldiers return to combat for multiple tours of duty.

    PTSD is a health condition that can result from wartime trauma such as being physically wounded or seeing others hurt or killed.

    Symptoms range from irritability and outbursts of anger to sleep difficulties, trouble concentrating, extreme vigilance and an exaggerated startle response. People with the condition can persistently relive the traumatic events that initially induced horror or helplessness.

    The Pentagon has come under mounting political pressure in recent years to enhance treatment for PTSD amid criticism that initial programs were inadequate.

    Earlier this month, Defense Secretary Robert Gates announced a change in the U.S. government clearance process that allows PTSD sufferers to seek help for combat-related mental health problems without risking their military careers.

    Army officials on Tuesday emphasized that the data do not reflect the actual number of troops and war veterans who suffer from PTSD, many of whom do not seek treatment or have been diagnosed at civilian facilities where records are confidential.

    A recent study by the RAND Corp. estimated about 300,000 troops, or 18.5 percent, of the more than 1.5 million troops sent to Iraq and Afghanistan exhibit symptoms of either PTSD or depression.

    The fresh statistics add detail about the scale of human suffering from two wars that have killed 4,579 U.S. troops and inflicted physical wounds on 32,076 more.

    There currently are 155,000 U.S. troops in Iraq and 33,000 in Afghanistan.

    --------

    (Editing by Will Dunham and Bill Trott)