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. 2015 May;123(5):445-50.
doi: 10.1289/ehp.1408535. Epub 2015 Jan 23.

Lead exposure and tremor among older men: the VA normative aging study

John S Ji  1 , Melinda C Power, David Sparrow, Avron Spiro 3rd, Howard Hu, Elan D Louis, Marc G Weisskopf
Affiliations

Lead exposure and tremor among older men: the VA normative aging study

John S Ji et al. Environ Health Perspect. 2015 May.

Abstract

Background: Tremor is one of the most common neurological signs, yet its etiology is poorly understood. Case-control studies suggest an association between blood lead and essential tremor, and that this association is modified by polymorphisms in the δ-aminolevulinic acid dehydrogenase (ALAD) gene.

Objective: We aimed to examine the relationship between lead and tremor, including modification by ALAD, in a prospective cohort study, using both blood lead and bone lead-a biomarker of cumulative lead exposure.

Methods: We measured tibia (n = 670) and patella (n = 672) bone lead and blood lead (n = 807) among older men (age range, 50-98 years) in the VA Normative Aging Study cohort. A tremor score was created based on an approach using hand-drawing samples. ALAD genotype was dichotomized as ALAD-2 carriers or not. We used linear regression adjusted for age, education, smoking, and alcohol intake to estimate the associations between lead biomarkers and tremor score.

Results: In unadjusted analyses, there was a marginal association between quintiles of all lead biomarkers and tremor scores (p-values < 0.13), which did not persist in adjusted models. Age was the strongest predictor of tremor. Among those younger than the median age (68.9 years), tremor increased significantly with blood lead (p = 0.03), but this pattern was not apparent for bone lead. We did not see modification by ALAD or an association between bone lead and change in tremor score over time.

Conclusion: Our results do not strongly support an association between lead exposure and tremor, and suggest no association with cumulative lead biomarkers, although there is some suggestion that blood lead may be associated with tremor among the younger men in our cohort.

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Conflict of interest statement

The contents of this paper are solely the responsibility of the authors. The views expressed in this paper do not necessarily represent the views of the VA.

The authors declare they have no actual or potential competing financial interests.

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