Utilizing T1-weighted MRI intensity indices to evaluate in-vivo neurotoxicity in a South African cohort with environmental manganese exposure

Susan R. Criswell, Department of Neurology, Barrow Neurological Institute, Phoenix, AZ, USA; Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA. Electronic address: susan.criswell@barrowneuro.org.
Irene Faust, Department of Neurology, Barrow Neurological Institute, Phoenix, AZ, USA.
Susan Searles Nielsen, Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.
Wendy W. Dlamini, Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA; Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA.
Gill Nelson, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown, South Africa.
Jay R. Turner, Department of Energy, Environmental, and Chemical Engineering, Washington University, St. Louis, MO, USA.
Joshua S. Shimony, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA.
Jason Lenox-Krug, Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.
Jordan A. Killion, Department of Neurology, Barrow Neurological Institute, Phoenix, AZ, USA.
T Noah Hutson, Department of Neurology, Barrow Neurological Institute, Phoenix, AZ, USA.
Brad A. Racette, Department of Neurology, Barrow Neurological Institute, Phoenix, AZ, USA; Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA; School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown, South Africa.

Document Type

Article

Abstract

BACKGROUND: Excessive exposure to manganese (Mn) causes parkinsonism. Occupational Mn exposure is associated with increased T1-weighted globus pallidus signal on magnetic resonance imaging (MRI) secondary to in-vivo Mn deposition. METHODS: The present study evaluated the T1-weighted pallidal index (PI) as an in-vivo marker of Mn exposure and neurotoxicity in chronic environmental Mn exposure. A total of 53 Black South African participants with a range of residential environmental Mn exposures due to proximity to one of the world's largest smelters underwent T1-weighted MRI. RESULTS: The PI was associated with parkinsonism as measured by the total Unified Parkinson's Disease Rating Scale motor subsection part 3 (UPDRS3) in all participants (β=0.10, confidence interval 0.01, 0.18). Further, the PI was positively associated with total UPDRS3 scores (β=0.14, confidence interval 0.03, 0.25) and the lower limb rigidity subscore (β=0.04, confidence interval 0.005, 0.07) among those who regularly consumed alcohol (>3 drinks/week), but not in those who occasionally consumed alcohol (<3 drinks/week). CONCLUSION: Our findings suggest T1-weighted PI is associated with clinical neurotoxicity in environmental Mn exposure. This association is amplified by regular consumption of alcohol.

Medical Subject Headings

Humans; Magnetic Resonance Imaging (methods); Manganese (toxicity); Male; South Africa; Female; Middle Aged; Environmental Exposure (adverse effects); Cohort Studies; Adult; Neurotoxicity Syndromes (diagnostic imaging); Aged

Publication Date

10-1-2025

Publication Title

Journal of trace elements in medicine and biology : organ of the Society for Minerals and Trace Elements (GMS)

E-ISSN

1878-3252

Volume

91

First Page

127732

PubMed ID

40907163

Digital Object Identifier (DOI)

10.1016/j.jtemb.2025.127732

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