Higher Hippocampal Diffusivity Values in Welders Are Associated with Greater R2* in the Red Nucleus and Lower Psychomotor Performance

Authors

Eun-Young Lee
Juhee Kim
Janina Manzieri Prado-Rico
Guangwei Du
Mechelle M Lewis
Lan Kong
Byoung-Gwon Kim
Young-Seoub Hong
Jeff D Yanosky
Richard B Mailman
Xuemei Huang

Publication Date

5-1-2023

Journal

Neurotoxicology

Abstract

INTRODUCTION: Chronic excessive welding exposure may be related to higher metal accumulation and structural differences in different subcortical structures. We examined how welding affected brain structures and their associations with metal exposure and neurobehavioral consequences.

METHODS: Study includes 42 welders and 31 controls without a welding history. Welding-related structural differences were assessed by volume and diffusion tensor imaging (DTI) metrics in basal ganglia, red nucleus (RN), and hippocampus. Metal exposure was estimated by both exposure questionnaires and whole blood metal levels. Brain metal accumulations were estimated by R1 (for Mn) and R2* (for Fe). Neurobehavioral status was assessed by standard neuropsychological tests.

RESULTS: Compared to controls, welders displayed higher hippocampal mean (MD), axial (AD), and radial diffusivity (RD) (p's < 0.036), but similar DTI or volume in other ROIs (p's > 0.117). Welders had higher blood metal levels (p's < 0.004), higher caudate and RN R2* (p's < 0.014), and lower performance on processing/psychomotor speed, executive function, and visuospatial processing tasks (p's < 0.046). Higher caudate and RN R2* were associated with higher blood Fe and Pb (p's < 0.043), respectively. RN R2* was a significant predictor of all hippocampal diffusivity metrics (p's < 0.006). Higher hippocampal MD and RD values were associated with lower Trail Making Test-A scores (p's < 0.025). A mediation analysis of both groups revealed blood Pb indirectly affected hippocampal diffusivity via RN R2* (p's < 0.041).

DISCUSSION: Welding-related higher hippocampal diffusivity metrics may be associated with higher RN R2* and lower psychomotor speed performance. Future studies are warranted to test the role of Pb exposure in these findings.

Keywords

Humans, Diffusion Tensor Imaging, Psychomotor Performance, Metal Workers, Lead, Red Nucleus, Occupational Exposure, Welding, Hippocampus

Comments

Supplementary Materials

PMID: 36966945