Study Suggests Brain Injuries May Evolve, Not Resolve, Over Time

Service members with concussions may have symptoms that continue to evolve up to five years after the initial injury, according to a study published in the November 11, 2020, online issue of Neurology®, the medical journal of the American Academy of Neurology. The findings challenge the idea that these individuals with chronic brain injuries maintain a relatively stable course of recovery.

“Careful examination of combat-deployed service members, from the point of injury to one and five years later identified an evolution, not resolution, of symptoms,” said study author Christine L. Mac Donald, PhD, of the University of Washington School of Medicine, in Seattle. “In particular, a proportion of patients did worse on neurobehavioral and psychiatric evaluations when comparing one to five years, demonstrating the need to consider that not all chronic brain injury patients have the same experience in the years post injury.”

The study involved 281 service members who were deployed to combat between 2008 and 2013. Four groups were evaluated: two groups of patients with combat-related concussion, one group with concussion from blasts and one with concussion from blunt traumas; and two groups of service members without brain injuries, one group with and another group without subconcussive blast exposure, which are blasts that do not reach the threshold of causing a concussion. Researchers then compared clinical outcomes after one and five years across the groups.

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Each evaluation included clinical examination of neurobehavioral and psychiatric symptoms as well as cognitive performance across a variety of functions such as memory, attention and executive function. In addition, researchers collected information about level of disability and quality of life.

Five years after injury, 30% of blast-exposed and 34% of non-blast exposed service members with concussions declined into a worse disability bracket compared to prior evaluations. Researchers found this notable because one year after injury, 79% of service members with concussions resulting from blast exposure and 78% of those with non-blast brain injuries were already in the moderate-to-severe disability range. Over the same time period, only 5% of service members without concussion or blast exposure similarly declined.

When researchers looked at participants’ psychiatric symptoms over five years, there was an increase in the number of service members suffering from moderate to severe impairment. For example, the research team found that the percentage of each group meeting the criteria for moderate to severe posttraumatic stress disorder (PTSD) symptoms increased during this time frame. At one year, 26% of service members with blast-related concussions fell into that category; at five years, 41% did. For service members with non-blast related concussions, 39% had moderate to severe PTSD at one year, 54% at five years. Of the group with subconcussive blast exposure, 25% reported moderate to severe PTSD at one year; 39% of them did at five years. And for the group without any blast exposure and no concussions, none of them reported moderate to severe PTSD symptoms one year into the study, but 9% did five years later.

“Our study suggests that clinicians should not lump all patients recovering from concussions together in the months, or even years, that follow an injury, as their symptoms may continue to evolve,” said Mac Donald. “The lingering effects may also complicate other conditions unrelated to the concussion as these service members age.”

Limitations of the study were the small number of participants in the exploratory groups and lack of complete medical documentation prior to the injury.

The study was supported by the National Institute of Neurological Disorders and Stroke.

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