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Effects of low-level sarin and cyclosarin exposure on white matter integrity in Gulf War Veterans.
Neurotoxicology. 2015 May; 48:239-48.N

Abstract

BACKGROUND

We previously found evidence of reduced gray and white matter volume in Gulf War (GW) veterans with predicted low-level exposure to sarin (GB) and cyclosarin (GF). Because loss of white matter tissue integrity has been linked to both gray and white matter atrophy, the current study sought to test the hypothesis that GW veterans with predicted GB/GF exposure have evidence of disrupted white matter microstructural integrity.

METHODS

Measures of fractional anisotropy and directional (i.e., axial and radial) diffusivity were assessed from the 4T diffusion tensor images (DTI) of 59 GW veterans with predicted GB/GF exposure and 59 "matched" unexposed GW veterans (mean age: 48 ± 7 years). The DTI data were analyzed using regions of interest (ROI) analyses that accounted for age, sex, total brain gray and white matter volume, trauma exposure, posttraumatic stress disorder, current major depression, and chronic multisymptom illness status.

RESULTS

There were no significant group differences in fractional anisotropy or radial diffusivity. However, there was increased axial diffusivity in GW veterans with predicted GB/GF exposure compared to matched, unexposed veterans throughout the brain, including the temporal stem, corona radiata, superior and inferior (hippocampal) cingulum, inferior and superior fronto-occipital fasciculus, internal and external capsule, and superficial cortical white matter blades. Post hoc analysis revealed significant correlations between higher fractional anisotropy and lower radial diffusivity with better neurobehavioral performance in unexposed GW veterans. In contrast, only increased axial diffusivity in posterior limb of the internal capsule was associated with better psychomotor function in GW veterans with predicted GB/GF exposure.

CONCLUSIONS

The finding that increased axial diffusivity in a region of the brain that contains descending corticospinal fibers was associated with better psychomotor function and the lack of significant neurobehavioral deficits in veterans with predicted GB/GF exposure hint at the possibility that the widespread increases in axial diffusivity that we observed in GW veterans with predicted GB/GF exposure relative to unexposed controls may reflect white matter reorganization after brain injury (i.e., exposure to GB/GF).

Authors+Show Affiliations

Center for Imaging of Neurodegenerative Diseases, San Francisco Veterans Affairs Medical Center, 4150 Clement Street, 114M, San Francisco, CA 94121, United States; Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States; Department of Psychiatry, University of California San Francisco, San Francisco, CA, United States. Electronic address: linda.chao@ucsf.edu.Center for Imaging of Neurodegenerative Diseases, San Francisco Veterans Affairs Medical Center, 4150 Clement Street, 114M, San Francisco, CA 94121, United States; Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States.Center for Imaging of Neurodegenerative Diseases, San Francisco Veterans Affairs Medical Center, 4150 Clement Street, 114M, San Francisco, CA 94121, United States.

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

25929683

Citation

Chao, Linda L., et al. "Effects of Low-level Sarin and Cyclosarin Exposure On White Matter Integrity in Gulf War Veterans." Neurotoxicology, vol. 48, 2015, pp. 239-48.
Chao LL, Zhang Y, Buckley S. Effects of low-level sarin and cyclosarin exposure on white matter integrity in Gulf War Veterans. Neurotoxicology. 2015;48:239-48.
Chao, L. L., Zhang, Y., & Buckley, S. (2015). Effects of low-level sarin and cyclosarin exposure on white matter integrity in Gulf War Veterans. Neurotoxicology, 48, 239-48. https://doi.org/10.1016/j.neuro.2015.04.005
Chao LL, Zhang Y, Buckley S. Effects of Low-level Sarin and Cyclosarin Exposure On White Matter Integrity in Gulf War Veterans. Neurotoxicology. 2015;48:239-48. PubMed PMID: 25929683.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of low-level sarin and cyclosarin exposure on white matter integrity in Gulf War Veterans. AU - Chao,Linda L, AU - Zhang,Yu, AU - Buckley,Shannon, Y1 - 2015/04/27/ PY - 2014/11/12/received PY - 2015/03/18/revised PY - 2015/04/20/accepted PY - 2015/5/2/entrez PY - 2015/5/2/pubmed PY - 2016/2/26/medline KW - Cyclosarin KW - Diffusion tensor imaging KW - Gulf War veterans KW - Sarin KW - White matter SP - 239 EP - 48 JF - Neurotoxicology JO - Neurotoxicology VL - 48 N2 - BACKGROUND: We previously found evidence of reduced gray and white matter volume in Gulf War (GW) veterans with predicted low-level exposure to sarin (GB) and cyclosarin (GF). Because loss of white matter tissue integrity has been linked to both gray and white matter atrophy, the current study sought to test the hypothesis that GW veterans with predicted GB/GF exposure have evidence of disrupted white matter microstructural integrity. METHODS: Measures of fractional anisotropy and directional (i.e., axial and radial) diffusivity were assessed from the 4T diffusion tensor images (DTI) of 59 GW veterans with predicted GB/GF exposure and 59 "matched" unexposed GW veterans (mean age: 48 ± 7 years). The DTI data were analyzed using regions of interest (ROI) analyses that accounted for age, sex, total brain gray and white matter volume, trauma exposure, posttraumatic stress disorder, current major depression, and chronic multisymptom illness status. RESULTS: There were no significant group differences in fractional anisotropy or radial diffusivity. However, there was increased axial diffusivity in GW veterans with predicted GB/GF exposure compared to matched, unexposed veterans throughout the brain, including the temporal stem, corona radiata, superior and inferior (hippocampal) cingulum, inferior and superior fronto-occipital fasciculus, internal and external capsule, and superficial cortical white matter blades. Post hoc analysis revealed significant correlations between higher fractional anisotropy and lower radial diffusivity with better neurobehavioral performance in unexposed GW veterans. In contrast, only increased axial diffusivity in posterior limb of the internal capsule was associated with better psychomotor function in GW veterans with predicted GB/GF exposure. CONCLUSIONS: The finding that increased axial diffusivity in a region of the brain that contains descending corticospinal fibers was associated with better psychomotor function and the lack of significant neurobehavioral deficits in veterans with predicted GB/GF exposure hint at the possibility that the widespread increases in axial diffusivity that we observed in GW veterans with predicted GB/GF exposure relative to unexposed controls may reflect white matter reorganization after brain injury (i.e., exposure to GB/GF). SN - 1872-9711 UR - https://www.unboundmedicine.com/medline/citation/25929683/Effects_of_low_level_sarin_and_cyclosarin_exposure_on_white_matter_integrity_in_Gulf_War_Veterans_ DB - PRIME DP - Unbound Medicine ER -