Impacts of dioxin exposure on brain connectivity estimated by DTI analysis of MRI images in men residing in contaminated areas of Vietnam

Pham Ngoc Thao; Muneko Nishijo; Pham The Tai; Tran Ngoc Nghi; Takashi Yokawa; Vu Thi Hoa; Tran Viet Tien; Nguyen Xuan Kien; Tran Hai Anh; Yoshikazu Nishino; Hisao Nishijo

doi:10.3389/fnins.2024.1344653

Impacts of dioxin exposure on brain connectivity estimated by DTI analysis of MRI images in men residing in contaminated areas of Vietnam

Front Neurosci. 2024 Apr 25:18:1344653. doi: 10.3389/fnins.2024.1344653. eCollection 2024.

Authors

Affiliations

¹ Department of Functional Diagnosis, Military Hospital 103, Vietnam Military Medical University, Ha Noi, Vietnam.
² Department of Epidemiology and Public Health, Kanazawa Medical University, Ishikawa, Japan.
³ Institute of Biomedicine and Pharmacy, Vietnam Military Medical University, Ha Noi, Vietnam.
⁴ Ministry of Health, Vietnamese Government, Hanoi, Vietnam.
⁵ Kobe BMA Laboratory, BioView Inc., Kobe, Japan.
⁶ Department of Infectious and Tropical Diseases, Military Hospital 103, Vietnam Military Medical University, Ha Noi, Vietnam.
⁷ Department of Military Medical Command and Organization, Vietnam Military Medical University, Ha Noi, Vietnam.
⁸ Department of Physiology, Vietnam Military Medical University, Ha Noi, Vietnam.
⁹ Department of Sport and Health Sciences, Faculty of Human Sciences, University of East Asia, Yamaguchi, Japan.

Abstract

Introduction: Effects of dioxin exposure on gray matter volume have been reported in previous studies, but a few studies reported effects of dioxin exposure on white matter structure. Therefore, this study was undertaken to investigate the impact of dioxin exposure on white matter microstructure in men living in the most severely dioxin-contaminated areas in Vietnam.

Methods: In 2019 brain MRI scans from 28 men living near Bien Hoa airbase were obtained at Dong Nai General Hospital, Vietnam, on a 3 T scanner using a conventional diffusion tensor imaging sequence. Two exposure markers were indicated by perinatal exposure estimated by assessment of maternal residency in a dioxin-contaminated area during pregnancy and by measurement of blood dioxin levels. A general linear model was used to compare fractional anisotropy (FA) values in 11 white matter tracts in both hemispheres between groups with and without perinatal dioxin exposure and groups with high and low blood dioxin levels after adjusting for covariates.

Results: The adjusted mean FA value in the left cingulum hippocampal part (CGH) was significantly lower in the perinatal dioxin exposure group compared with the group without perinatal dioxin exposure. The high blood TCDD group showed significantly reduced FA values in the left and right CGH and right uncinate fasciculus (UNC). Moreover, the high blood TEQ-PCDDs group showed significantly lower FA values in the left and right CGH and the left UNC. There were no significant differences in FA values between the groups with high and low TEQ-PCDFs levels or between the groups with high and low TEQ-PCDD/Fs levels.

Discussion: It was concluded that dioxin exposure during the perinatal period and adulthood may alter the microstructure of white matter tracts in individuals with neurodevelopmental disorders.

Keywords: Vietnam; diffusion tensor imaging; dioxin; fractional anisotropy; neurodevelopment.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported partly by the Ministry of Education, Sports, Science and Culture, Japan, Grant-in-Aid for Scientific Research (17H04665 and 18K19709). These funders played no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.