title: Lead exposure and tremor among older men: the VA normative aging study.
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.
  
  
  CONCLUSIONS
  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.
authors: Department of Environmental Health, and Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.
authors: John S
authors: JS
authors: Ji
authors: Melinda C
authors: MC
authors: Power
authors: David
authors: D
authors: Sparrow
authors: Avron
authors: A
authors: Spiro
authors: Howard
authors: H
authors: Hu
authors: Elan D
authors: ED
authors: Louis
authors: Marc G
authors: MG
authors: Weisskopf
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004781:Environmental Exposure / Q000032:analysis*; D006801:Humans; D007854:Lead / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014202:Tremor / Q000097:blood*
chemical_list: D007854:Lead
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