Traumatic brain injury (TBI), the signature injury of military veterans of Iraq and Afghanistan, does not necessarily lead to Alzheimer's disease, according to research groups at the University of Washington and the San Francisco Veterans Affairs (VA) Health Care System.
A great majority of studies have linked TBI with an increased risk of developing Alzheimer's, but two recent publications indicate otherwise, said Dr. Michael Weiner from San Francisco in a press release by the U.S. Department of Veterans Affairs.
The first study examined the VA medical records of patients with a history of brain injury in conjunction with biomarkers of Alzheimer's. By observing structural changes to the brain on MR images and the presence of amyloid plaques on PET scans, Weiner and colleagues found that there was no correlation between TBI and Alzheimer's.
The second study also demonstrated that a history of TBI did not trigger Alzheimer's; instead, it was associated with other neurodegenerative diseases -- Lewy body disease and Parkinson's disease. This research, led by Dr. Paul Crane from Washington, involved nearly 1,600 patients who underwent brain autopsies from 1994 to 2014.
Whereas prior research may have been limited by the "self-report" approach to gathering patient history of TBI, as well as physicians' clinical assessments of Alzheimer's, the two current studies employed the technique of measuring biomarkers.
"Our preliminary results, and the results of Crane et al, suggest that the thought of a link between TBI and Alzheimer's may not be as strong as previously thought," Weiner said. "It might not exist at all."
Wiener called for a similar, albeit larger, study of veterans who have a history of brain injury to further clarify the relationship between TBI and Alzheimer's.
