Whole-brain mapping of increased manganese levels in welders and its association with exposure and motor function
Humberto Monsivais,
Chien-Lin Yeh,
Alex Edmondson,
Roslyn Harold,
Sandy Snyder,
Ellen M. Wells,
Tobias Schmidt-Wilcke,
Dan Foti,
S. Elizabeth Zauber,
Ulrike Dydak
Affiliations
Humberto Monsivais
School of Health Sciences, Purdue University, West Lafayette, IN, USA
Chien-Lin Yeh
School of Health Sciences, Purdue University, West Lafayette, IN, USA
Alex Edmondson
Cincinnati Children's Hospital Medical Center, Imaging Research Center, Cincinnati, OH, USA; University of Cincinnati College of Medicine, Department of Environmental and Public Health Sciences, Cincinnati, OH USA
Roslyn Harold
Department of Psychological Sciences, Purdue University, West Lafayette, IN, USA
Sandy Snyder
School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Speech, Language and Hearing Sciences, Purdue University, West Lafayette, IN, USA
Ellen M. Wells
School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Public Health, Purdue University, West Lafayette, IN, USA
Tobias Schmidt-Wilcke
Department of Neurology, St. Mauritius Therapieklinik, Meerbusch, Germany; Institute of Clinical Neuroscience and Medical Psychology, Universitätsklinikum Düsseldorf, Düsseldorf, Germany
Dan Foti
Department of Psychological Sciences, Purdue University, West Lafayette, IN, USA
S. Elizabeth Zauber
Department of Neurology, Indiana University School of Medicine, Indianapolis, USA
Ulrike Dydak
School of Health Sciences, Purdue University, West Lafayette, IN, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA; Corresponding author at: School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47906, USA.
Although manganese (Mn) is a trace metal essential for humans, chronic exposure to Mn can cause accumulation of this metal ion in the brain leading to an increased risk of neurological and neurobehavioral health effects. This is a concern for welders exposed to Mn through welding fumes. While brain Mn accumulation in occupational settings has mostly been reported in the basal ganglia, several imaging studies also revealed elevated Mn in other brain areas. Since Mn functions as a magnetic resonance imaging (MRI) T1 contrast agent, we developed a whole-brain MRI approach to map in vivo Mn deposition differences in the brains of non-exposed factory controls and exposed welders. This is a cross-sectional analysis of 23 non-exposed factory controls and 36 exposed full-time welders from the same truck manufacturer. We collected high-resolution 3D MRIs of brain anatomy and R1 relaxation maps to identify regional differences using voxel-based quantification (VBQ) and statistical parametric mapping. Furthermore, we investigated the associations between excess Mn deposition and neuropsychological and motor test performance. Our results indicate that: (1) Using whole-brain MRI relaxometry methods we can generate excess Mn deposition maps in vivo, (2) excess Mn accumulation due to occupational exposure occurs beyond the basal ganglia in cortical areas associated with motor and cognitive functions, (3) Mn likely diffuses along white matter tracts in the brain, and (4) Mn deposition in specific brain regions is associated with exposure (cerebellum and frontal cortex) and motor metrics (cerebellum and hippocampus).
