MINNEAPOLIS – Experiencing a traumatic brain injury (TBI) ups the risk 60% for older veterans to later develop dementia, according to a recent study.
The report, published recently in the journal Neurology, also found that, among all veterans developing dementia, veterans with a history of TBI developed cognitive issues about two years earlier than those without that type of head injury.1
“These findings suggest that a history of TBI contributes risk for dementia in later life in veterans. If we assume that this relationship is causal, it seems likely that the same increased risk probably occurs with TBI in the civilian population, as well,” said lead author Deborah E. Barnes, PhD, MPH, of the San Francisco VAMC and the University of California, San Francisco.
Study background notes that TBI “is common in military personnel, and there is growing concern about the long-term effects of TBI on the brain; however, few studies have examined the association between TBI and risk of dementia in veterans.”
The research involved 1,229 veterans with a TBI diagnosis identified through a retrospective cohort study of 188,784 veterans who, at the beginning of the research, were an average age of 68, free of dementia and had received VA treatment.
During the nine-year follow-up period, 196 veterans with TBI, about 16%, developed dementia, compared with 18,255, or 10% of those without TBI. After adjusting for other factors that could affect the risk of dementia, including diabetes, high blood pressure, depression and alcohol abuse, researchers determined that veterans with TBI were 60% more likely to develop dementia than those without TBI.
Researchers also identified an additive association between TBI and other conditions –depression, post-traumatic stress disorder or cerebrovascular disease — on risk of developing dementia.
On average, veterans with TBI developed dementia two years earlier than those without TBI, or at age 78.5 compared with 80.7, the authors write. Also, those who did not develop dementia died 2.3 years earlier if they had a TBI vs. no TBI (77.0 years vs. 79.3 years).
“TBI in older veterans was associated with a 60% increase in the risk of developing dementia over nine years after accounting for competing risks and potential confounders,” the authors concluded. “Our results suggest that TBI in older veterans may predispose toward development of symptomatic dementia and raise concern about the potential long-term consequences of TBI in younger veterans and civilians.”
The author of an accompanying editorial suggested that the research is persuasive.
“This study convincingly shows that mild trauma has a role in increasing the risk of dementia and sheds light on the more complex relationship between medical and psychiatric diseases with TBI in the development of the future risk of dementias. Neuroscientists must take a careful and comprehensive approach and avoid oversimplified claims of causality,” wrote Rodolfo Savica, MD, MSc, of the University of Utah School of Medicine in Salt Lake City.
1 Barnes DE, Kaup A, Kirby KA, Byers AL, Diaz-Arrastia R, Yaffe K. Traumatic brain injury and risk of dementia in older veterans. Neurology. 2014 Jun 25. pii: 10.1212/WNL.0000000000000616. [Epub ahead of print] PubMed PMID: 24966406.