Chronic low-level mercury exposure, BDNF polymorphism, and associations with cognitive and motor function

Diana Echeverria, James S. Woods, Nicholas J. Heyer, Dianne S. Rohlman, Federico M. Farin, Alvah C. Bittner, Tingting Li, Claire Garabedian

Research output: Contribution to journalArticlepeer-review

98 Scopus citations


Potential cognitive and motor effects from exposure to elemental mercury (Hg0) were examined in the presence and absence of a polymorphism (Val66Met) in brain-derived neurotrophic factor (BDNF). A group of 194 male dentists (DDs) and 233 female dental assistants (DAs) were occupationally exposed to mercury and had no history of kidney or nervous system disorders. Acute exposure was measured using spot urinary Hg (HgU) concentrations (average 3.32 and 1.98 μg/l, respectively) and indices of chronic occupational exposure (26.3 and 14.9 years, respectively, weighted for historical exposures). The BDNF status was 68% and 66% wild type, 26% and 30% single substitution, and 5% and 4% full mutation for DDs and DAs, respectively. DDs and DAs were evaluated separately. Regression analyses controlled for age, premorbid intelligence, alcohol consumption, and education. Statistically significant adverse associations with HgU (p < .05) were found for nine measures among DDs (Digit Span Forward, Digit and Spatial SpanBackward, Visual Reproduction, Finger Tapping Dominant, Alternate, and Alternate Partialed, Hand Steadiness, and Tracking), and eight measures among DAs (Digit SpanForward, Visual Reproduction, Pattern DiscriminationRate, Symbol Digit Rate, Trailmaking B, Finger Tapping Dominant and Alternate Partialed, and Hand Steadiness). The BDNF status was associated with four measures in DDs and three measures in DAs. Joint effects were found for Finger Tapping Alternate and Alternate Partialed in DDs and Hand Steadiness and Trailmaking B in DAs. Joint effects were additive in all cases. Performance on verbal intelligence and reaction time were not associated with either HgU or BDNF status. A test of threshold effect for the association of Hand Steadiness with HgU demonstrated no lower boundary in both DDs and DAs. No associations were observed with estimates of chronic mercury exposure. Our findings are applicable to exposure levels of the general population and identify a potentially vulnerable group with a BDNF polymorphism.

Original languageEnglish (US)
Pages (from-to)781-796
Number of pages16
JournalNeurotoxicology and Teratology
Issue number6
StatePublished - Nov 2005
Externally publishedYes


  • Attention
  • BDNF polymorphism
  • Mercury
  • Motor function
  • Short-term memory
  • Threshold

ASJC Scopus subject areas

  • Toxicology
  • Developmental Neuroscience
  • Cellular and Molecular Neuroscience


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