“Stroke is a disease which is at the junction between neurological and cardiovascular health,” said Holly Elser, an epidemiologist and resident physician in neurology at the hospital of the University of Pennsylvania, who conducted the study.
The findings “raise the intriguing possibility that individuals with head injury may benefit from evidence-based stroke prevention methods such as lowering blood cholesterol levels or blood pressure if they are elevated,” she added.
The scientists compared the rate of stroke diagnosis of those with earlier head injuries to those without prior head trauma and found a 32 percent increase of ischemic stroke among those who had suffered a head injury. Individuals with two or more head injuries had a 94 percent greater chance of stroke, compared with those with no head injury, the study showed.
The as-yet-unpublished research, presented at the annual meeting of the American Neurological Association in September, analyzed data from the Atherosclerosis Risk in Communities (ARIC) Study in 12,813 U.S. adults recruited between 1987 and 1989.
The ARIC is a prospective study — one that follows people over time — that has gathered health data related to atherosclerosis and cardiovascular disease for more than 30 years on participants in four U.S. communities — Forsyth County, N.C.; Jackson, Miss.; eight northern suburbs of Minneapolis; and Washington County, Md.
After 30 years, 2,158 people had suffered a head injury — 73 percent of them mild — and, of those with a head injury, 147 ultimately had an ischemic stroke, Elser said. Thirty-four people with stroke had a history of more than one head injury, she said.
While the study wasn’t designed to directly examine the mechanisms linking head injury to future stroke, Elser said head injury may lead to local and systemic inflammation and vascular changes that increase risk. Or it may be that behavior changes after a head injury, such as decreased physical activity, increase risk.
What the experts are saying
Andrew E. Budson, chief of cognitive and behavioral neurology and associate chief of staff for education at the VA Boston Healthcare System, who was not involved in the study, said that it was unclear how the scientists defined a TBI.
“My suspicion is that the TBI had to be significant and wouldn’t be relevant to people who hit their heads on cabinet doors or children who play soccer,” he said.
Kevin Sheth, professor of neurology and neurosurgery at the Yale School of Medicine, who also was not involved in the research, called the study “provocative” but said additional evidence was needed to establish the link.
“We cannot know for sure that head trauma plays a causal role in incident stroke,” Sheth said.
There were more than 69,000 TBI-related deaths in the United States in 2021, according to the Centers for Disease Control and Prevention. They can result from a fall — a significant risk factor for older people — firearms use, motor vehicle crashes, assaults, sports-related trauma, such as in football and soccer, and during military action.
Every year, millions of Americans older than 65 experience falls, according to the CDC. This translates to 1 in 4 older adults falling, resulting in more than 800,000 emergency department visits, with 1 in 5 of the falls resulting in serious injuries such as broken hips or other bone fractures, or head trauma, according to the CDC. Falls are the leading cause of injury and death in this age group, the CDC says.
“Head injuries are associated with long-term morbidity and increased mortality risk, and our study underscores the importance of head injury prevention through strategies to reduce risk of falls in older adults and through measures like seat belt laws,” Elser said.
She said it was important for older adults to speak with their physicians about their fall risk and consider — if necessary — the use of assistive devices such as canes and walkers.
“For individuals who are not at risk for falls, preventive measures should include steps like always wearing a seat belt in the car and wearing a helmet while cycling,” she said.