Military doctors have issued a new test for combat troops who may have suffered brain injuries following reports that they have been cheating on the exams so they can stay on the battlefield.

Doctors at the Defense and Veterans Brain Injury Center (DVBIC) changed certain questions to a test used to diagnose concussions because cheating on it could put servicemen and women, as well as their comrades, in danger.

"If a teacher found kids cheating, the teacher would come up with different tests. It's the same idea," said Chuck Dasey, a spokesman with the Walter Reed Army Medical Center.

The test, called the Military Acute Concussion Evaluation (MACE), is administered to service members in combat who have suffered blows to the head, often after bomb blasts have thrown them into nearby surfaces.

Military doctors have administered the oral evaluation since 2000 at the scene of an accident or bombing or shortly after an incident occurs in the field.

Soldiers have been supplying each other with answers to prior exams so they can pass and remain with their units.

Part of the test requires memory recall of a series of simple words. On the old examination, doctors would read a list of words including "elbow," "apple" and "bubble" and ask the patient to say them in any order. The exercise is done three times initially, and then again later to see if patients can still remember the words.

Click here to see the old test.

The updated version of the MACE exam, with new lists of words, has already been distributed, according to Dasey.

"The easy solution was just to develop additional or alternate word lists," said Dasey. "It's a valid diagnostic tool, and it's being used a lot. We wanted to keep it effective."

The problem appears to be occurring within all branches of the military. The soldiers who are cheating think they're doing the noble thing by trying to stay in combat, according to the DVBIC and Dasey.

"These are highly motivated service members who would rather remain deployed with their units than be medically evacuated for treatment for concussion," the DVBIC said in a statement.

But their actions could put them and others in their unit in harm's way, especially if they've suffered repeated concussions — which become more dangerous with each additional strike to the head.

"Army doctors are aware of the cumulative effects of the concussions," Dasey said. "That's one reason that there's significant effort to protect the soldiers. They want to prevent people from having multiple concussions and getting hurt worse."

Troop leaders know that injured soldiers who beat the diagnostic exam may make costly mistakes when they return to battle, but many of the soldiers and Marines who cheat may not be fully cognizant of the possible consequences — and if they are, they may be willing to take that chance.

"Some of these guys are pretty young. They might be risk takers," said Dasey.

The Navy, the Marine Corps and the Army all declined to comment about the trend.

Dasey likened the phenomenon to one that has been found among football players, who have similarly cheated on concussion tests in order to remain on the playing field.

"[Troops] identify with their fellow soldiers or Marines," Dasey said of the service members at war. "That's their family. That's who they want to stay with."

The DVBIC's test also includes questions about what happened; what they remember and don't remember; whether they were dazed, confused or "saw stars"; whether they were wearing a helmet; and whether they blacked out.

Medics inquire about other symptoms that can accompany head trauma, including nausea or vomiting, headache, dizziness, balance problems and a ringing in the ears, and they physically examine a patient's eye movement and motor coordination.

Brain injuries from explosions are fairly common among service members fighting in Iraq and Afghanistan.

Serious head trauma is often accompanied by clear-cut symptoms, including open, bleeding wounds; a brief or longer-term period of mental confusion; a loss of consciousness; and the sensation of seeing stars.

Milder injuries are difficult to detect and treat because the signs can be vague or nonexistent, even though the accumulation of minor hits to the head can lead to significant brain damage.

That's where the concussion evaluation comes in.

"This test is for people who don't have an obvious, serious injury," Dasey said. "In severe cases, you can tell."

The changes to the exam seem to be working, said Dasey. He said there have been no reports of cheating "that I am aware of" since the word recall section was altered.

"The introduction of new content (lists, etc.) has resolved the problem," he said.

Walter Reed Army Medical Center was at the heart of a scandal earlier this year over its alleged neglect of wounded soldiers as well as reports of squalid conditions and sub-par care and staffing in some parts of the hospital.