The neurotoxic effects of Agent Orange have important implications for the long-term brain health not only of veterans, but of all people exposed to biologically similar herbicides.
PROVIDENCE, R.I. [Brown University] -Agent Orange, an herbicide used during the Vietnam War, is a known toxin with wide-ranging health effects. Even though Agent Orange has not been used for decades, there is increasing interest in its effects on the brain health of aging veterans. A new study by scientists at Brown University reveals the mechanisms by which Agent Orange affects the brain and how those processes can lead to neurodegenerative diseases.
The research shows that exposures to Agent Orange herbicidal chemicals damage frontal lobe brain tissue of laboratory rats with molecular and biochemical abnormalities that are similar to those found in early-stage Alzheimer's disease. An early online version of this paper detailing the findings was published on Feb. 13 and is scheduled for publication in the Journal of Alzheimer's Disease.
The findings could have important implications for military veterans who were exposed to Agent Orange during the Vietnam War, said study author Dr. Suzanne M. De La Monte, a Brown University physician-scientist.
"If we can show that prior exposure to Agent Orange leads to subsequent neurodegenerative disease, then that gives veterans a chance to get help," De La Monte said.
But the study's findings have much broader significance, she added, because the toxins in Agent Orange are also present in lawn fertilizers.
"These chemicals don't just affect veterans; they affect our entire population," said De La Monte, who is a professor of pathology and laboratory medicine and neurosurgery at Brown's Warren Alpert Medical School.
Agent Orange is a synthetic defoliating herbicide that was widely used between 1965 and 1970 during the Vietnam War. Members of the U.S. military were exposed to the chemical when stationed close to enemy territory that had been sprayed by aircraft. Government reports show that exposure to Agent Orange also caused birth defects and developmental disabilities in babies born to Vietnamese women residing in the affected areas. Over time, studies showed that exposure to Agent Orange was associated with an increased risk of some cancers as well as cardiovascular disease and diabetes.
Research also revealed associations between Agent Orange exposures and later development of nervous system degenerative diseases, and significantly higher rates and earlier onsets of dementia. However, in the absence of a proven causal link between Agent Orange and aging-associated diseases, there has been a need for studies that improve understanding of the process by which the herbicide affects the brain.
"Scientists realized that Agent Orange was a neurotoxin with potential long-term effects, but those weren't shown in a clear way," De La Monte said. "That's what we were able to show with this study."
The analysis was conducted by De La Monte and Dr. Ming Tong, a research associate in medicine at Brown; both are also associated with Rhode Island Hospital, an affiliate of the Warren Alpert Medical School. Their research builds upon their recent studies of exposure to Agent Orange chemicals on immature human cells from the central nervous system showing that short-term exposure to Agent Orange has neurotoxic and early degenerative effects related to Alzheimer's.
