As many as 20 percent of U.S. combat troops who fought in Iraq or Afghanistan leave with signs they may have had a concussion, and some do not realize they need treatment, Army officials said Thursday.

Concussion is a common term for mild traumatic brain injury, or TBI. While the Army has a handle on treating more severe brain injuries, it is "challenged to understand, diagnose and treat military personnel who suffer with mild TBI," said Brig. Gen. Donald Bradshaw, chairman of a task force on traumatic brain injury created by the Army surgeon general.

The task force, which completed its work in May, released its findings on Thursday.

It estimated that from 10 percent to 20 percent of soldiers and Marines from tactical units leaving Iraq and Afghanistan are affected by mild traumatic brain injury. The most common cause was blast from an explosion.

The symptoms can include headaches, dizziness, nausea, light sensitivity, sleep problems, memory problems, confusion and irritability. With treatment, more than 80 percent of patients recover completely, the task force said.

Fewer than half who suffered from a mild traumatic brain injury in combat have persistent symptoms associated with it, said Col. Robert Labutta, a neurosurgeon with the Army surgeon general's office.

In some cases, however, symptoms from the injury such as irritability affect a soldier's interaction with his or her family and fellow soldiers, said Col. Jonathan Jaffin, deputy commander of the U.S. Army Medical Research and Materiel Command.

"By identifying them, giving them a diagnosis, so they don't think they're just going crazy ... we think that helps them deal with it," Jaffin said.

Thousands of troops have been treated for traumatic brain injury, and it is commonly called the signature wound of the war. Reports that troops were not properly treated or diagnosed for the injury led to some improvements in care.

Today, all troops brought to military treatment facilities from a war zone are screened for traumatic brain injury, Bradshaw said. But troops lacking more outward signs such as bleeding after a blast or other incident might not realize they had experienced a concussion, Bradshaw said.

One of the challenges in treating a mild traumatic injury is that it can have some of the same symptoms as post-traumatic stress disorder, such as difficulty sleeping.

Labutta said more research and tracking is needed to determine if a mild traumatic brain injury can put someone at greater risk for Alzheimer's disease and Parkinson's disease.

The task force praised work done at an Army fort in Colorado, where soldiers going back to war are screened for brain injury. Surveys there found that about 17 percent of the soldiers returning to war could have a traumatic brain injury.

The task force identified problems associated with the treatment of troops with traumatic brain injuries, such as inconsistent treatment and documentation at some facilities, but it said some of its recommendations have already been implemented.