"The Defense Department has determined that based on current Purple Heart criteria, PTSD is not a qualifying Purple Heart wound," department spokeswoman Eileen Lainez said.
"PTSD is an anxiety disorder caused by witnessing or experiencing a traumatic event," Lainez said. It is not "a wound intentionally caused by the enemy from an outside force or agent."
The Defense Department statement announcing the decision, released Tuesday, said the Purple Heart has never been awarded for mental disorders of psychological conditions.
Veterans diagnosed with PTSD "still warrant appropriate medical care and disability compensation, Lainez said, and the department "is working hard to encourage service members and their families to seek care for PTSD by reducing the stigma and urging them to seek professional care."
Last month, CBS News correspondent Kimberly Dozier reported on the astoinishing number of soldiers coming back from war to face new horrors at home. The Pentagon says 1 in 5 service members who come home from Iraq or Afghanistan suffer from post-traumatic stress, Dozier reported.
Some find their experiences too much to bear. There were 115 military suicides in 2007, and 93 through August of 2008.
The biggest obstacle to getting those numbers down may be the military culture itself, according to Dozier's report. Commanders at one army base posted a fake "Hurt Feelings Report" - portraying a crying cartoon face - to mock soldiers seeking help for combat stress. Selections on the form included: "I am a crybaby," "I want my mommy" and "All of the above." It was tacked on the barracks bulletin board, next to the sign-up sheet, for the mental health clinic.
CBS News correspondent Randall Pinkston reported on a veteran's movement to change the requirements for earning a Purple Heart in June 2008.
Former Marine Lieutenant Robert Muller, a Vietnam vet who was wounded in the the line of duty and has been bound to a wheel chair ever since, has a Purple Heart, Pinkston reported.
"Took a bullet through the chest and that qualified," said Muller.
As head of a veteran's advocacy group, Muller thinks PTSD victims should also be eligible for the Purple Heart, a medal traditionally only given for physical injuries, not psychological illnesses.
"We're not talking about an illness, we're talking about an injury," said Muller. "If you go to war and you have psychic trauma, that's injury."
The Purple Heart has been around for more than two centuries - General George Washington made the first presentations. The criteria for receiving the award have changed several times.
Supporters of changing the rules for awarding Purple Hearts say it could be one way of removing the stigma some soldiers feel about admitting they are suffering from mental illness, Pinkston reported.