Military veterans who suffer traumatic brain injury could experience an increased long-term risk of stroke.
The alarming possibility comes from a new study presented at the American Heart Association’s 2022 Epidemiology and Prevention, Lifestyle and Cardiometabolic Health conference. Prior studies have previously shown short-term associations between brain injury and stroke, according to Dr. Andrea Schneider, lead researcher of the latest study.
This particular study used data gathered from more than 610,000 veterans; and found those who had a head injury were 69% more likely to suffer a stroke. That risk was highest within the first year following injury but remained elevated for about a decade. Plus, risk was higher in those who had more severe injuries. These findings illustrated that “this risk persists for years after injury,” said Schneider, assistant professor of neurology and epidemiology at the University of Pennsylvania Perelman School of Medicine in Philadelphia.
A traumatic brain injury is one that results in unconsciousness, confusion, amnesia or other neurological symptoms. About 450,000 service members were diagnosed with a traumatic brain injury between 2000 and 2021, according to the Department of Defense. Schneider said military personnel are exposed to specific risks, such as explosions, that can lead to these types of serious injuries. In the general population, people could experience brain injuries playing sports or in motor vehicle accidents. Among older people, falls are the most common cause of such injuries.
To explore how traumatic brain injuries may relate to stroke, Schneider and her colleagues looked at data from 306,796 people in a Veterans Health Administration database who had a traumatic brain injury within the timeframe of October 2002 to September 2019. They compared those people’s risk for stroke to an equal number of people who had not had a brain injury.
Researchers calculated 10.3 strokes per 1,000 people per year among those with traumatic brain injuries. That’s compared to 5.7 strokes per 1,000 people per year in those without brain injuries. After adjusting for factors such as income, education, smoking status and medical and psychiatric conditions, the researchers found a traumatic brain injury significantly increased the risk of stroke by 69%.
The increased risk varied by type of stroke. For an ischemic stroke – the most common type, where blood flow to the brain is blocked – the risk was 56% higher in the veterans with traumatic brain injuries compared to those without. For a hemorrhagic stroke – which causes bleeding in the brain – the risk was nearly four times higher in those with brain injuries. The findings are considered preliminary.
Dr. Mitch Elkind, a neurologist at New York-Presbyterian Hospital/Columbia University Irving Medical Center in New York City, said the more immediate increased risk of stroke after brain trauma may be related to damage such as torn arteries. “But this study provides evidence that traumatic head injury may lead to a long-term increased risk of both ischemic and, particularly, hemorrhagic stroke,” said Elkind, past president of the AHA. However, he was not involved in the study.
The findings should prompt further studies to identify the reasons behind the connection, he said. “It may be that head injury is another insult, like the transient inflammation associated with infection, that increases long-term stroke risk.”
It’s possible that unmeasured factors such as medication use – or lack thereof – could account for these results, he shared. Survivors of traumatic brain injuries, for example, may be more likely, “if they have associated cognitive problems, to be less adherent to medications for hypertension.”
Schneider agreed further research is needed but said the findings suggest people with brain injuries should be aware of the possibility of permanent damage that may affect their blood vessels. They should be extra aware of risk factors that can be controlled, such as high blood pressure, diabetes and high cholesterol.
“We want everybody’s diabetes and blood pressure to be controlled,” she said. “But what this research may suggest is that maybe it’s even more important in people who’ve had a traumatic brain injury.”