UW study links past military service to Alzheimer’s disease

November 16, 2023

The brains of deceased military veterans had higher levels of two abnormal proteins considered hallmarks of Alzheimer’s disease, suggesting that military veterans face a greater risk for developing Alzheimer’s, according to a new study from the University of Wisconsin School of Medicine and Public Health.

The study was recently published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association led by Ryan Powell, PhD, MA, assistant professor of medicine, UW School of Medicine and Public Health.

The study found that military veterans who had donated their brains to Alzheimer’s disease research centers had 26 percent greater odds of having amyloid plaques in their brains than nonveterans and 10 percent greater odds of having neurofibrillary tangles made of abnormal tau proteins, according to Powell. The findings, as well as prior research showing higher frequency of Alzheimer’s disease risk factors among veterans, support a rationale for greater support in disease prevention and treatment interventions for this population.

“To our knowledge, this is the first study to link a history of military service to Alzheimer’s disease neuropathology, the gold standard for diagnosing Alzheimer’s,” said Powell, who is data science director of the UW Center for Health Disparities Research. “This has important implications for the Veterans Health Administration since it indicates an urgent need to screen veterans and to target therapies to those at greatest risk.”

Powell and his research collaborators looked at brain biopsy data from 597 males who died between 1986 and 2018 and donated their brains to Alzheimer’s disease research centers at the UW School of Medicine and Public Health and the University of California San Diego.

Genealogical archivists used genealogy databases, census and military records to determine that about 60 percent of the males had served in the military — most likely during World War II, Korean War and Vietnam War eras. The rate of military service was consistent between those who donated brains in San Diego and in Madison, Powell said.

The group of 358 male veterans had higher levels of both amyloid plaques and tau tangles in their brains, both biomarkers of Alzheimer’s disease. Researching female veteran risk is a key next step but researchers were unable to conduct this analysis given the small number of them represented in the current study, Powell said.

“This study is shining new light on data that’s been collected over decades — some donations date all the way back to the mid-1980s — so the donations of these veterans are still yielding valuable new insights after all these years,” he said. “We identified the ‘who’ and the ‘what’ in this study, but we need to narrow in on the ‘why’ and the ‘when.’”

Veterans are exposed to many known risks for brain disorders, including chronic stress from physical and psychological pain, physical trauma including traumatic brain injuries and environmental hazards such as Agent Orange, a tactical defoliating agent used in Vietnam. In addition, veterans have higher rates of cardiovascular disease, depression and PTSD, all of which are known risk factors for dementia, Powell said.

Exposures during military service and differences in life both before and after service likely all contribute to the brain disease, he explained. Researchers hope to expand the study to other brain banks to gain a deeper understanding and include younger generations of veterans to unlock the root causes of these brain changes in veterans, he said.

“We might be able to uncover other factors and learn where risks can be reduced,” Powell said. “And with new Alzheimer’s therapies coming online, there’s a need for scientific-based health equity policies to get them to those who might benefit most. It’s exciting that this ongoing line of research can inform policy changes that improve the health of veterans.”

The study was supported by funding from the National Institutes of Health – National Institute on Aging (grants R21AG079277, R01AG070883, P30AG062715, R01AG079303, and P30AG066530).