Title: Association of neurobehavioral performance with R2* in the caudate nucleus of asymptomatic welders.

Authors: Lee, Eun-Young; Eslinger, Paul J; Flynn, Michael R; Wagner, Daymond; Du, Guangwei; Lewis, Mechelle M; Kong, Lan; Mailman, Richard B; Huang, Xuemei

Published In Neurotoxicology, (2017 Jan)

Abstract: 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.

PubMed ID: 27871916

MeSH Terms: Adult; Analysis of Variance; Caudate Nucleus/diagnostic imaging; Caudate Nucleus/metabolism*; Cohort Studies; Executive Function/physiology; Female; Humans; Imaging, Three-Dimensional; Iron/blood; Iron/metabolism*; Language; Magnetic Resonance Imaging; Male; Maze Learning/physiology; Middle Aged; Neuropsychological Tests; Psychomotor Disorders/chemically induced*; Sex Characteristics; Verbal Learning; Welding*