Associations Between Neurological Diseases and Dioxin Exposure Originating from Agent Orange in Vietnam: A Narrative Review

Now, half a century after the Vietnam War, Agent Orange exposure during the war is increasingly discussed as a risk factor for neurological diseases, particularly dementia and Alzheimer’s disease, among Korean and U.S. Vietnam War veterans. Emerging evidence supports associations between dioxin exposure originating from Agent Orange and alterations in brain morphology and function among Vietnamese residents, including children living in areas around former U.S. airbases exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) after the Vietnam War. This paper summarizes what is known about the effects of Agent Orange exposure in the context of neurological disorders, including Alzheimer’s disease, Parkinson’s disease, autism spectrum disorder, attention-deficit/hyperactivity disorder, and psychiatric disorders. Molecular biological studies have reported that TCDD may increase the risks of these neurological diseases by accelerating brain aging and inducing atypical neurodevelopment, partly mediated by the aryl hydrocarbon receptor. However, the effects of TCDD, which is a highly toxic contaminant of Agent Orange, as well as dioxin congeners other than TCDD, exhibit some inconsistencies. This review aims to provide new insights for mitigating the adverse neurological effects of dioxin exposure from Agent Orange, contributing to a healthier life for residents in Vietnam.