title: Elevated blood lead concentrations in essential tremor: a case-control study in Mersin, Turkey.
abstract: BACKGROUND
  Essential tremor (ET) is one of the most common neurologic disorders. Aside from underlying susceptibility genes, recent studies have also begun to focus on environmental toxic factors. Yet there remains a paucity of information on such factors, making studies of environmental factors important. A recent study in New York City found blood lead concentrations to be elevated in ET cases compared with matched controls. Chronic exposure to lead produces cerebellar damage, and this could predispose individuals to develop ET.
  
  
  OBJECTIVE
  The aim of this study was to determine whether the elevation in blood lead concentrations observed in a single study in New York was similarly present in ET cases sampled from a completely different geographic region.
  
  
  METHODS
  Blood lead concentrations were measured in 105 ET cases and 105 controls at Mersin University, Mersin, Turkey.
  
  
  RESULTS
  The median blood lead concentration was 2.7 microg/dL in ET cases compared with 1.5 microg/dL in controls (p < 0.001). In an unadjusted logistic regression model, blood lead concentration was associated with diagnosis: odds ratio (OR) = 4.01; 95% confidence interval (CI), 2.53-6.37; p < 0.001 (i.e., each 1-microg/dL increase in blood lead concentration was associated with a 4-fold increased odds of ET). This association was more robust when cases were compared with a subsample of controls who did not share the same home environment (OR = 8.13; 95% CI, 3.05-21.65; p < 0.001). In adjusted models, results were similar.
  
  
  CONCLUSIONS
  These data replicate those of a previous study in New York and demonstrate an association between the environmental toxicant lead and a common neurologic disorder.
authors.affiliation: Department of Neurology, Faculty of Medicine, Mersin University, Mersin, Turkey.
authors.forename: Okan
authors.initials: O
authors.lastname: Dogu
authors.forename: Elan D
authors.initials: ED
authors.lastname: Louis
authors.forename: Lulufer
authors.initials: L
authors.lastname: Tamer
authors.forename: Ozgur
authors.initials: O
authors.lastname: Unal
authors.forename: Arda
authors.initials: A
authors.lastname: Yilmaz
authors.forename: Hakan
authors.initials: H
authors.lastname: Kaleagasi
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D020329:Essential Tremor / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007854:Lead / Q000097:blood*; D007855:Lead Poisoning / Q000150:complications*; D016015:Logistic Models; D008297:Male; D014421:Turkey; D014743:Videotape Recording
chemical_list: D007854:Lead