BURLINGTON, VT—Parkinson’s disease (PD) might present somewhat differently in the VA’s healthcare system than in many community medical facilities. Why? Because PD can fall into several different cat- egories. It can be: • a service-connected condition for U. S. veterans, with presumptive connection for those who served in specific locations or timeframes, • a non-presumptive service connection for those whose symptoms began during active military service, within one year of leaving service or • a condition related to a traumatic brain injury (TBI). “These service connections are based on evidence supporting an elevated risk of PD in association with environmental toxins or TBI, both of which can occur as occupational exposures during military service,” according to a recent study led by the University of Vermont Medical Center in Burlington and involving the Parkinsons Disease Research, Education, and Clinical Center (PADRECC) at the VA Portland, OR, Healthcare System. “Some neurotoxins, such as MPTP (1-methyl- 4-phenyl-1,2,3,6-tetrahydropyridine), rotenone, para- quat, and Agent Orange (AO), have been shown to induce PD pathophysiology through various mecha- nisms, including mitochondrial dysfunction, genera- tion of superoxide free radicals, and dopaminergic cell death. ”1 The authors pointed out that, among these, AO is considered the most significantly associated with PD in the context of U. S. veterans. The pesticide widely used during the Vietnam War is composed of 2,4-dichloro- phenoxyacetic acid (2,4-D) and 2,4,5-trichlorophen- oxyacetic acid (2,4,5-T), as well as dioxin (2,3,7,8-tet- rachlorodibenzo-p-dioxin (TCDD). The researchers noted that increasing evidence indicates that exposure to AO is associated with neu- rologic disorders, especially neurodegeneration and parkinsonism. That history of AO exposure can make PD a presumptive service-connected disease for U. S. veterans, making them eligible to receive healthcare and disability compensation. Back in 2016, a retrospective clinical research study in Korean veterans suggested that PD patients with history of exposure to AO exhibited different clinical phenotypes compared to those without such history of exposure. 2 The authors of the recent study noted, “However, to the best of our knowledge, no prospective data are available on potential differences in PD with a history of AO exposure in U. S. veterans,” but said they sought to answer that question. Their multicenter, prospective cohort study was conducted at the University of Vermont Medical Center (UVMMC), VA Portland Healthcare System (VHAPORHCS) and Oregon Health Science University (OHSU). The researchers recruited a total of 100 patients, 50 from each site, although two subjects were excluded because their AO exposure history was unknown. The primary grouping variable, history of AO exposure, was 31. 63 % (31 out of 98) from the VHAPORHCS/OHSU site (n = 28). It was determined by asking patients to recall whether they had any exposure, which was com- plemented with VA records to ensure accuracy. The secondary grouping variable, veteran sta- tus 44. 9 % (44 out of 98) was determined based on the patient’s enrollment in VA healthcare, irrespec- tive of their VA service connection for PD or any Parkinson’s Disease Might Be Somewhat Different In Veterans Exposed to Agent Orange When Deployed “ These service connections are based on evidence supporting an elevated risk of PD in association with environmental toxins or TBI, both of which can occur as occupational exposures during military service... ” By Brenda L. Mooney 2 0 2 6 C O M P E N D I U M O F F E D E R A L M E D I C I N E 6 5
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