WASHINGTON (AP)  Nearly 40,000 military personnel have been given diagnoses of post-traumatic stress disorder since 2003, Pentagon records show.

Officials say they believe that many other cases exist and have been encouraging service members to obtain help, even if they go to private therapists and do not report it to the military. The 40,000 cases are those tracked by the military.

Officials have also estimated that half the military personnel with mental problems do not receive treatment because they are embarrassed or fear that it might hurt their careers.

A report on diagnosed cases released on Tuesday by the Army surgeon general, Lt. Gen. Eric B. Schoomaker, showed that the hardest-hit services last year were the Marines and Army, the two forces bearing the brunt of combat in Iraq and Afghanistan.