Association of neurobehavioral performance with R2 in the caudate nucleus of asymptomatic welders

• Published in: Neurotoxicology (Park Forest South) 2017-01, Vol.58, p.66-74
• Main Authors: Lee, Eun-Young, Eslinger, Paul J., Flynn, Michael R., Wagner, Daymond, Du, Guangwei, Lewis, Mechelle M., Kong, Lan, Mailman, Richard B., Huang, Xuemei
• Format: Article
• Language: English
• Subjects: Adult; Amygdala; Analysis of Variance; Basal ganglia; Brain; Caudate nucleus; Caudate Nucleus - diagnostic imaging; Caudate Nucleus - metabolism; Chemical elements; Cognitive performance; Cohort Studies; Correlation analysis; Executive Function - physiology; Exposure; Female; Fumes; Ganglia; Globus pallidus; Heavy metals; Human exposure; Humans; Image processing; Imaging, Three-Dimensional; Iron; Iron - blood; Iron - metabolism; Iron accumulation; Language; Magnetic Resonance Imaging; Male; Manganese; Maze Learning - physiology; Measurement methods; Middle Aged; Nervous system; Neuroimaging; Neuropsychological Tests; Neurotoxicity; Nuclei; Occupational exposure; Phonemic fluency; Psychomotor Disorders - chemically induced; Putamen; Sex Characteristics; Verbal Learning; Welders; Welding; Welding fumes; Welding machines
• ISSN: 0161-813X; 1872-9711
• DOI: 10.1016/j.neuro.2016.11.007

•Welders had higher R2* (an estimate of Fe accumulation) in the caudate nucleus (CN) and lower performance on Phonemic Fluency test.•Welders’ Phonemic Fluency scores were inversely correlated with R2* in the CN but not with PI or R1s (estimates of Mn accumulation) of any basal ganglia areas.•Phonemic Fluency decline in welders may be due to higher Fe than Mn deposition. Welding fumes contain several metals including manganese (Mn) and iron (Fe) that may affect the nervous system. Previous studies of potential welding-related neurotoxicity have focused primarily on Mn exposure. The current study examined neurobehavioral and brain imaging changes in asymptomatic welders and their associations with both Mn and Fe exposure measurements. Data were obtained from subjects with (n=46) and without (controls; n=31) a history of welding exposure. Occupational questionnaires estimated recent (HrsW; welding hours and E90; cumulative exposure, past 90days) and lifetime (YrsW; total welding years and ELT; cumulative exposure, lifetime) exposure. Brain MRI pallidal index (PI), R1 (1/T1), and R2* (1/T2*) were measured to estimate Mn and Fe concentrations in the basal ganglia [caudate nucleus (CN), putamen, and globus pallidus], amygdala, and hippocampus. Comprehensive neuropsychological tests were conducted to examine behavioral differences between welders and controls. Correlation analyses were conducted between neuropsychological tests and those exposure measurements that showed significant group differences. Compared to controls, welders had significantly higher R2* in the CN and lower performance on the Phonemic Fluency test. Correlation analyses revealed that welders’ Phonemic Fluency scores were inversely associated with R2* in the CN, but not with the PI or R1 in any brain region of interest studied. The results showed that neurobehavioral performance for the asymptomatic welders in our study was worse than individuals who had not welded, and suggest the differences may be associated with higher Fe accumulation in the CN.