The U.S. Army report indicated enlisted soldiers on their third or fourth tours of duty showed signs of depression or other disorders in higher proportions than those on their first or second deployments, the Los Angeles Times reported Friday.

This study is the first to draw conclusions about troops on their third or fourth tours, the authors said. The information likely will increase calls by senior Army officials to reduce the length of combat tours and increase the time between deployments, the Times reported.

The report showed 27.2 percent of non-commissioned officers -- sergeants who lead troops in combat -- reported mental health problems such as depression, anxiety and stress disorder during their third or fourth tours. The percentage was 18.5 percent of those on their second tour and 11.9 percent of those on their first tour.

"Soldiers are not resetting entirely before they get back into theater," said U.S. Army Lt. Col. Paul Bliese, study team leader. "They're not having the opportunity to completely recover from the previous deployment when they go back into theater for the second or third deployment."