Military Personnel With Brain Injury At Risk For Long-Term Health Problems

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Military personnel who suffer severe or moderate traumatic brain injury (TBI) face an increased risk for developing several long-term health problems, says a new report from the Institute of Medicine that evaluates the evidence on long-term consequences of TBI. These conditions include Alzheimer's-like dementia, aggression, memory loss, depression, and symptoms similar to those of Parkinson's disease. Even mild TBI is associated with some of these adverse consequences, noted the committee that wrote the report.

In addition, the report notes that brain injuries sustained as a result of exposure to the force of an explosion without a direct strike to the head -- one of the most common perils for soldiers in Iraq and Afghanistan -- may be underdiagnosed due to the lack of research on blast injury. It calls for the U.S. Department of Defense and the U.S. Department of Veterans Affairs to step up clinical and animal studies of blast-induced neurotrauma (BINT).

"Explosive devices and other weaponry have become more powerful and devastating throughout the wars in Iraq and Afghanistan, and we are seeing much higher rates of nonpenetrating traumatic brain injury and blast-induced injury among military personnel who have served in these countries than in earlier wars," said George W. Rutherford, professor of epidemiology and preventive medicine and vice chair, department of epidemiology and biostatistics, School of Medicine, University of California, San Francisco, and chair of the committee that wrote the report. "It is important to identify and understand any long-term health effects of these injuries so that wounded service members do not lose valuable time for therapy and rehabilitation."

As of January, more than 5,500 military personnel have suffered TBIs during the conflicts in Iraq and Afghanistan, according to DOD. The prolific use of explosive weaponry in Iraq has made blast-related injuries the signature wound of the war, with many service members having been exposed to multiple explosions.

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Although recent clinical findings and military experience have shown that short-term and long-term neurologic deficits may result from exposure to the energy of a blast without a direct blow to the head, the prevailing opinion among neurological professionals had been that blast-related impairments were rare because the skull adequately shields the brain. The report recommends that VA and DOD support research on BINT and the development of a good animal model of BINT, which is currently lacking. Without good research data, neurological and behavioral changes in blast victims may be underestimated and undiagnosed, and these individuals may not get timely needed treatment, the report notes.

TBI can be mild, moderate, or severe. The committee's review of the research on TBI at all levels of severity determined that there is sufficient evidence that brain injuries resulting from severe, skull-piercing wounds can cause unprovoked seizures and premature death. Seizures can also be caused by severe, nonpenetrating TBI as well as more moderate brain injury.

Studies link both moderate and severe TBI with other long-term consequences, including increased risk for Alzheimer's-like dementia, symptoms similar to those of Parkinson's disease, and diminished abilities to maintain social relationships. Other data links mild TBI to increased risk for PTSD among Gulf War veterans. The evidence in these cases shows an association, but it is not sufficient to conclude that TBI causes these problems. Likewise, TBI at any level of severity -- even mild -- appears to be associated with increased risk for aggressive behavior, depression, and memory and concentration problems.

TBI may be associated with certain other potential consequences, but the evidence is only suggestive of a link. For example, moderate and severe TBI may put individuals at greater risk for developing diabetes insipidus and psychosis, but the evidence is limited. Some data suggest that mild TBI accompanied by loss of consciousness is linked to the development of symptoms similar to Alzheimer's and Parkinson's disease as well as vision problems and seizures, but the data have significant shortcomings. Likewise, TBI at all levels of severity may be linked to reduced alcohol and drug use within the first few years following the injury, but there is inadequate evidence to be certain.

Due to insufficient evidence, it is not possible to say whether mild TBI can result in neurocognitive deficits or loss of ability to function socially. Also, the evidence does not indicate whether mild TBI that was not accompanied by loss of consciousness could lead to the development of Alzheimer's-like dementia, or whether any TBI is linked to mania, bipolar disorder, multiple sclerosis, or amyotrophic lateral sclerosis.

To develop a fuller picture of the effects of TBI and blast injuries, the committee recommended that DOD conduct pre-deployment neurocognitive tests of all military personnel to establish a baseline for identifying post-injury consequences and that the VA include uninjured service members and other comparison groups in the Traumatic Brain Injury Veterans Health Registry which it is building.

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