Traumatic Brain Injury More Than Doubles Dementia Risk
July 19, 2011
Patients diagnosed with traumatic brain injury (TBI) had over twice the
risk of developing dementia within seven years after diagnosis compared
to those without TBI, in a study of more than 280,000 older veterans
conducted by researchers at the San Francisco VA Medical Center (SFVAMC)
and the University of California, San Francisco (UCSF).
Kristine Yaffe, MD
“This finding is important because TBI is so common,” said senior
investigator Kristine Yaffe, MD, chief of geriatric psychiatry at SFVAMC
and professor of psychiatry, neurology and epidemiology at UCSF. She
noted that about 1.7 million Americans are diagnosed with TBI each year.
In addition, she said, TBI is often referred to as the “signature wound”
of the wars in Iraq and Afghanistan, where it accounts for 22 percent of
casualties overall and affects up to 59 percent of troops exposed to
The study authors analyzed the medical records of 281,540 veterans age
55 or older who received care through the VA from 1997 to 2000 and did
not have a prior history of dementia. They found that 15 percent of
veterans who received a diagnosis of TBI developed dementia by 2007,
compared with 7 percent of those not diagnosed with TBI. Even after
controlling for factors such as age, medical history and cardiovascular
health, the authors found that a TBI diagnosis still doubled the risk of
The findings were presented at the 2011 Alzheimer’s Association
International Conference on Alzheimer’s Disease in Paris, France.
Lead author Deborah Barnes, PhD, a mental health researcher at SFVAMC,
said that the study is one of the first to examine the association
between dementia and different types of TBI diagnosis, including
intra-cranial injuries, concussion, post-concussion syndrome and skull
fracture. “It didn’t matter what type of diagnosis it was – they were
all associated with an elevated risk of dementia,” said Barnes, also an
associate professor of psychiatry at UCSF.
The authors speculated that among potential causes for the increased
risk, the most plausible is that TBI is associated with diffuse axonal
injury, or swelling of the axons that form connections between neurons
in the brain. This swelling, explained Yaffe, is accompanied by the
accumulation of proteins, including beta-amyloid, which is a hallmark of
Alzheimer’s disease. “The loss of axons and neurons could result in
earlier manifestation of Alzheimer’s symptoms,” said Yaffe.
Barnes said that for veterans, the findings have different implications
depending on the age of the veteran. “Older veterans who have had some
kind of head injury should be monitored over time, so that if signs of
dementia develop, treatment can begin as soon as possible,” she said.
“For younger veterans, early treatment and rehabilitation following TBI
may help prevent the development of dementia over the long term.”
Co-authors are Kristine R. Krueger, PhD, of the South Texas Veterans
Health Care System; Amy L. Byers, PhD, MPH, of SFVAMC and UCSF; and
Ramon Diaz-Arrastia, MD, MPH, of the University of Texas Southwestern
The research was supported by funds from the Department of Defense that
were administered by the Northern California Institute for Research and
NCIRE - The Veterans Health Research Institute - is the largest research
institute associated with a VA medical center. Its mission is to improve
the health and well-being of veterans and the general public by
supporting a world-class biomedical research program conducted by the
UCSF faculty at SFVAMC.
SFVAMC has the largest medical research program in the national VA
system, with more than 200 research scientists, all of whom are faculty
members at UCSF.
UCSF is a leading university dedicated to promoting health worldwide
through advanced biomedical research, graduate-level education in the
life sciences and health professions, and excellence in patient care.
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