An independent study released Thursday by the Rand Corp. reveals that 20 percent of military service members who have returned from Iraq and Afghanistan are suffering from major depression or post traumatic stress disorder (PTSD).

The 300,000 veterans involved in the study all suffered head injuries from mild concussions to severe wounds. So far, only half of them have sought treatment.

"There is a major health crisis facing those men and women who have served our nation in Iraq and Afghanistan," said Terri Tanielian, the project's co-leader and a researcher at the Rand Corp., according to the Associated Press.

"Unless they receive appropriate and effective care for these mental health conditions, there will be long-term consequences for them and for the nation," she said in a statement.

Following reports of increased mental health problems, the Army said it had been raising the number of soldier screenings. But the Rand study argues that mental problems of several soldiers might go undetected, escaping the bureaucratic system.

It is very possible that some soldiers avoid seeking help out of fear that their career would be ruined or their colleagues would not trust them anymore.

"When we asked folks what was limiting them from getting the help that they need, among the top barriers that were reported were really negative career repercussions," Tanielian said.

That is why the study recommends finding ways in which mental healthcare is provided confidentially so the ill service members do not have to disclose their private matters to superior officers.

One of the main causes of the increasing incidence of traumatic brain injury is represented by the troops’ exposure to roadside bombs in Iraq and Afghanistan.

TBI, or traumatic brain injury, is considered one of the “invisible wounds” of the war, and the Rand study tries to make people more aware of the issue, helping them to better understand the way it affects their lives.

"These conditions can impair relationships, disrupt marriages, aggravate the difficulties of parenting, and cause problems in children that may extend the consequences of combat trauma across generations," the study reads.

Lisa H.Jaycox, one of the study’s authors, warns the United States that the failure to treat depression and other similar diseases could cost the country around $6 billion.