Dec. 21 (HealthDay News) -- Brain-injured Vietnam war veterans experience a faster decline in cognitive functioning as they age than veterans without such trauma, a new study finds.

The study looked at 199 Vietnam veterans who suffered penetrating head injuries during the war and had been followed since 1967.

Researchers found that the rate of cognitive decline in these veterans can be predicted by how intelligent they were before their brain injury, their level of education, the size and location of the injury, and certain genetic markers linked with brain injury and neurodegeneration.

Greater intelligence and a higher level of education before the brain injury were associated with a lesser decline in cognitive functioning in subsequent years, the study found.

These findings are important in light of the high prevalence of brain injuries suffered by American soldiers in Iraq and in Afghanistan, the researchers reported in the Dec. 19 online edition of the journal Brain.

"Nearly two-thirds of injured U.S. soldiers sent from Iraq to the U.S. army medical center have been diagnosed with traumatic brain injuries," study author Dr. Jordan Grafman, senior investigator in the Cognitive Neuroscience Section at the National Institute of Neurological Disorders and Stroke, noted in a prepared statement.

"The additional burden of accelerated cognitive decline to brain-injured veterans should be considered when estimating their future health care needs. These veterans would benefit from lifelong care by neurologists and specialists in head injury. Particularly as they age, given their injury, they may have greater needs than others, and the health care system, if prepared for this, can essentially shadow these soldiers," Grafman said.

He and his colleagues said doctors "treating veterans with brain injuries should evaluate any changes in their neurobehavioral status carefully so as not to confuse an exacerbated decline in function with dementia."

SOURCE: National Institute of Neurological Disorders and Stroke, Dec. 19, 2007