US Vietnam War Vets Exposed To Agent Orange Are Twice As Likely To Get Dementia

Forests in Tay Ninh and An Loc being sprayed with chemical defoliant by the US military during the Vietnam War era. Image credit: Everett Collection/Shutterstock.com

In a new study of over 300,000 US veterans, researchers found that those exposed to Agent Orange during the Vietnam War were nearly twice as likely to be diagnosed with dementia than those who weren't.

As part of its chemical warfare program, Operation Ranch Hand, the US sprayed over 12 million gallons of the potent herbicide Agent Orange, along with other chemical defoliants, onto the dense forests of Southeast Asia over the course of the Vietnam War (1955-1975) with the aim of stripping the Viet Cong of food and cover. 

This act of war left a horrific legacy, resulting in thousands of US soldiers and people in Vietnam developing liver diseases, cancers, skin problems, birth abnormalities, and metabolic disorders. Much of these health complications are closely linked to the herbicide's active ingredient TCDD, a highly toxic dioxin and a known human carcinogen. 

New research published in the journal JAMA Neurology highlights one of the clearest links yet between Agent Orange exposure and dementia. Scientists at the San Francisco Veterans Affairs Health Care System looked at the medical records of over 300,000 veterans of the Vietnam era and found that exposure to Agent Orange was associated with approximately a 2-fold increased risk of being diagnosed with dementia. This remained true even after adjusting for other factors, such as the demographic variables, medical conditions, and psychiatric conditions that might also play a role in the development of dementia.

The observational study didn’t look to understand why Agent Orange might have this link to dementia, but the researchers suggest a few possible mechanisms. Previous research suggested that dioxin has been found in the blood and fat of Vietnam veterans decades after exposure to Agent Orange. This, they suggest, may increase the risk of diabetes and Parkinson's disease, which are two well-known and established dementia risk factors. Furthermore, dioxin is also neurotoxic and can affect the brain's hypothalamus and the pituitary gland through nervous tissue damage induced by oxidative stress and indirect damage to the brain’s blood supply. This kind of damage to the brain can also increase the risk of dementia. 

The Vietnam War ended over 45 years ago, but the scale of the problems left behind by Agent Orange is still only beginning to be recognized. In 2019, a study found that the problematic dioxin TCDD continues to lurk in the environment in Vietnam. It's also still likely making its way into the food supply by lingering in water systems, consumed by bottom-feeding fish and shrimp, which are then eaten by larger fish. These fish are then caught and widely eaten in Vietnam and other countries in Southeast Asia.

Just this week, a French-Vietnamese journalist is appearing in a French court to accuse 14 companies that supplied the US with Agent Orange of causing harm to her and her children. The landmark case is also seeking recognition of the damage caused by Agent Orange to the natural environment. 

"I'm not fighting for myself, but for my children and the millions of victims," said Tran To Nga, the 78-year-old journalist filing the case, reported AFP.

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