WEDNESDAY, June 25, 2014 (HealthDay News) -- Military veterans who have experienced a traumatic brain injury may be more prone to developing dementia, new research suggests.
In fact, they were 60 percent more likely to be diagnosed with dementia sooner than those who never had a brain injury.
""Our results suggest that [brain injury] may increase the risk of developing dementia in older veterans, with an age of onset about two years earlier. So clinicians may want to keep an eye out for signs of cognitive impairment in older veterans with a history of [brain injury]," said study author Deborah Barnes, an associate professor in the department of psychiatry at the University of California, San Francisco, School of Medicine.
However, the study was only able to point to an association, not cause-and-effect.
The researchers evaluated almost 190,000 veterans who were 68 years old, on average, and dementia-free. Of those vets, 1,229 had been diagnosed with a brain injury. The researchers then looked at data from those veterans over a nine-year follow-up period. They found that 16 percent of those with a brain injury developed dementia, while only 10 percent of those without a brain injury did.
The researchers also took other risk factors into consideration such as diabetes, high blood pressure, depression and alcohol abuse.
The researchers found that veterans who had a brain injury developed dementia at 78.5 years old, on average, while dementia did not set in for those without a brain injury until an average age of almost 81.
The risk for developing dementia was higher in veterans with a brain injury who also experienced depression, post-traumatic stress disorder (PTSD) or cerebrovascular disease, compared to those who had either a brain injury or any one of those conditions.
The findings are published online June 25 in the journal Neurology.
While the researchers did not study the specific mechanism that might cause an increased risk of dementia, Barnes had a theory about how it might work. She explained that each "hit" to the brain reduces the brain's ability to bounce back after being damaged. Another theory is that a brain injury leads to a build-up of amyloid or tau, the proteins that are implicated in Alzheimer's disease and other dementias.
Mark Kaplan, a professor of social welfare at the University of California, Los Angeles, said the new study "highlights an emerging public health crisis." He also noted that genetic, behavioral and environmental factors can interact with head traumas to boost the risk for dementia.
Kaplan believes these patients should be screened for depression and suicidality, alcohol misuse and access to firearms. Their caregivers are also at risk for depression and suicide, which expands the problem to an even greater population, he added.
To learn more about traumatic brain injury and dementia, please visit American Academy of Neurology.
SOURCES: Deborah Barnes, Ph.D., M.P.H., associate professor, department of psychiatry, University of California, San Francisco; Mark Kaplan, Dr.P.H., professor of social welfare, Luskin School of Public Affairs, University of California, Los Angeles; June 25, 2014, Neurology