During the 19 years of the Vietnam War, the United States waged a roughly decade-long “herbicidal warfare” program — a campaign called Operation Ranch Hand. Agent Orange was the most commonly used “tactical-use” herbicide and defoliant. About half a century later, the powerful chemical still casts a long shadow: New research suggests that veterans exposed to Agent Orange are at heightened risk of developing dementia.
In a massive aerial campaign during the Vietnam War, the United States Air Force sprayed nearly 19 million gallons of herbicides in South Vietnam to strip the enemy of vegetation cover and food supplies. Roughly 11 million gallons of those chemicals were a highly toxic defoliant called Agent Orange. While it was banned by the U.S. in 1971, people exposed to it continue to suffer from related health effects today, ranging from heart disease and skin disorder to various types of cancers.
Now, a new study suggests that Agent Orange exposure could also elevate people’s likelihood of developing dementia. The research shows that U.S. veterans exposed to the herbicide are almost twice as likely to receive a dementia diagnosis than those without exposure.
“Vietnam veterans and family members should be aware that exposure to Agent Orange may increase risk of developing dementia and that symptoms of dementia may begin at a younger age,” Deborah Barnes, an author of the study and a researcher with the Department of Veterans Affairs and the University of California San Francisco, wrote in an email to Being Patient. “Consequently, Vietnam veterans should be adequately screened and treated for dementia in later life.”
In the recent study published in JAMA Neurology, Barnes and colleagues combed through electronic health records of more than 300,000 veterans who served between 1964 to 1975. About 12 percent of them were presumed to be exposed to Agent Orange.
Veterans with documented exposure to the chemical had roughly double the risk of developing dementia compared to those without. The association held up even after the researchers adjusted for demographics, medical conditions (i.e. diabetes, traumatic brain injury and Parkinson’s) and psychiatric conditions (i.e. depression, post-traumatic stress disorder and substance use disorder). Exposed veterans remained nearly twice as likely to be diagnosed with dementia, and they were about 15 months younger than unexposed veterans.
Dr. Paul Rosenberg of Johns Hopkins University told Medscape Medical News that the recent study demonstrates a “meaningful increase” in dementia risk associated with Agent Orange exposure, using robust methods and a large sample.
But, he said veterans exposed to Agent Orange may live less healthy lifestyles later in life, which would also put them at greater risk of developing dementia, though the variables could not be controlled for in the study.
“Although veterans can’t change their past, they can control
their future activities. It is possible that the increased risk of
dementia associated with Agent Orange exposure could be
offset by engaging in a healthy lifestyle.”
While it remains unclear why Agent Orange is associated with dementia, Barnes and colleagues suggested that the human carcinogen in Agent Orange known as dioxin could be a culprit. According to the researchers, the storage of dioxin in fat tissue may stimulate biological responses implicated in health conditions like diabetes and Parkinson’s, leading to a subsequent increase in dementia risk.
As fat tissue may release the toxin over time, Barnes told JAMA Neurology in an interview that dioxin could potentially cause toxic effects on the brain.
A 2018 report by the National Academies of Sciences, Engineering and Medicine, determined that Agent Orange could be associated with a host of health conditions, several of which — like high blood pressure (backed by strong evidence), diabetes and Parkinson’s disease (both are supported by limited evidence) — are also risk factors of dementia.
The two latter conditions, as well as other illnesses such as heart disease, skin disorder and various types of cancers, are under the Veteran’s Association’s list of illnesses “caused by exposure to Agent Orange,” which makes it easier for veterans to get disability compensation.
“When sound medical and scientific evidence shows that an illness is caused by Agent Orange exposure, we add it to our list of presumptive diseases,” the VA website reads. “If you’ve been diagnosed with one of these illnesses, you don’t need to prove that it started during—or got worse because of—your military service.” Last year, lawmakers added bladder cancer, hypothyroidism and Parkinson’s-like symptoms to the list, and some are now pushing to include high blood pressure as well.
However, Barnes said few studies so far have directly examined any direct link between Agent Orange and dementia. The authors of the 2018 report concluded there was not enough evidence to prove that the herbicide is tied with heightened risk of dementia, and the VA currently does not include dementia in its list of illnesses presumed to be caused by Agent Orange exposure.
Barnes noted that further research is needed not only to confirm the study’s findings, but to better understand the factors that influence dementia risk associated with Agent Orange, before it would be possible to reach any conclusions.
Providing quality data is critical to informing the VA’s policy as families are waiting for answers and looking for greater access to health care. One spouse of a veteran exposed to Agent Orange commented on a recent VA news release, noting that her loved one receives little benefits for the care services he needs for his dementia diagnosis.
Barnes also hopes to see more research into how veterans exposed to the chemical could reduce their heightened risk of developing dementia. After all, Barnes said that treatment for comorbidities and lifestyle interventions such as exercise, cognitively stimulating activities and social interaction have all been shown to potentially decrease dementia risk.
“Although veterans can’t change their past, they can control their future activities,” Barnes said. “It is possible that the increased risk of dementia associated with Agent Orange exposure could be offset by engaging in a healthy lifestyle.”
Meanwhile, Dr. Rosenberg urged veterans who were exposed to Agent Orange to be especially attuned to the early signs of cognitive impairment and to see their primary care clinicians if they notice any red flags.
Contact Nicholas Chan at firstname.lastname@example.org