Association of MRI T1 relaxation time with neuropsychological test performance in manganese- exposed welders

R M Bowler; C-L Yeh; S W Adams; E J Ward; R E Ma; S Dharmadhikari; S A Snyder; S E Zauber; C W Wright; U Dydak

doi:10.1016/j.neuro.2017.05.010

Association of MRI T1 relaxation time with neuropsychological test performance in manganese- exposed welders

Neurotoxicology. 2018 Jan:64:19-29. doi: 10.1016/j.neuro.2017.05.010. Epub 2017 Jun 3.

Authors

R M Bowler¹, C-L Yeh², S W Adams³, E J Ward⁴, R E Ma², S Dharmadhikari⁵, S A Snyder⁶, S E Zauber⁷, C W Wright³, U Dydak⁸

Affiliations

¹ San Francisco State University, Department of Psychology, 1600 Holloway Ave., San Francisco, CA 94132, USA. Electronic address: rbowl@sfsu.edu.
² School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 950 W. Walnut Street, Indianapolis, IN, 46202, USA.
³ San Francisco State University, Department of Psychology, 1600 Holloway Ave., San Francisco, CA 94132, USA.
⁴ School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907, USA.
⁵ Department of Radiology and Imaging Sciences, Emory University Hospital,1364 Clifton Road, Atlanta, GA, 30322, USA.
⁶ School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907, USA; Department of Speech, Language and Hearing Sciences, Purdue University, 715 Clinic Drive, West Lafayette, IN 47907, USA.
⁷ Department of Neurology, Indiana University School of Medicine, 355 W 16th St, Indianapolis, IN 46202, USA.
⁸ School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907, USA; Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 950 W. Walnut Street, Indianapolis, IN, 46202, USA; Department of Speech, Language and Hearing Sciences, Purdue University, 715 Clinic Drive, West Lafayette, IN 47907, USA. Electronic address: udydak@purdue.edu.

Abstract

This study examines the results of neuropsychological testing of 26 active welders and 17 similar controls and their relationship to welders' shortened MRI T1 relaxation time, indicative of increased brain manganese (Mn) accumulation. Welders were exposed to Mn for an average duration of 12.25 years to average levels of Mn in air of 0.11±0.05mg/m³. Welders scored significantly worse than controls on Fruit Naming and the Parallel Lines test of graphomotor tremor. Welders had shorter MRI T1 relaxation times than controls in the globus pallidus, substantia nigra, caudate nucleus, and the anterior prefrontal lobe. 63% of the variation in MRI T1 relaxation times was accounted for by exposure group. In welders, lower relaxation times in the caudate nucleus and substantia nigra were associated with lower neuropsychological test performance on tests of verbal fluency (Fruit Naming), verbal learning, memory, and perseveration (WHO-UCLA AVLT). Results indicate that verbal function may be one of the first cognitive domains affected by brain Mn deposition in welders as reflected by MRI T1 relaxation times.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Adult
Brain / diagnostic imaging*
Brain / pathology
Humans
Magnetic Resonance Imaging
Male
Manganese Poisoning / diagnosis*
Manganese Poisoning / pathology
Manganese Poisoning / psychology
Middle Aged
Neuropsychological Tests
Occupational Exposure*
Welding*

Abstract

Publication types

MeSH terms

Grants and funding