Low-level inorganic arsenic exposure and neuropsychological functioning in American Indian elders

Environ Res. 2017 Jul;156:74-79. doi: 10.1016/j.envres.2017.03.018. Epub 2017 May 12.

Abstract

Background: Inorganic arsenic at high and prolonged doses is highly neurotoxic. Few studies have evaluated whether long-term, low-level arsenic exposure is associated with neuropsychological functioning in adults.

Objectives: To investigate the association between long-term, low-level inorganic arsenic exposure and neuropsychological functioning among American Indians aged 64-95.

Methods: We assessed 928 participants in the Strong Heart Study by using data on arsenic species in urine samples collected at baseline (1989-1991) and results of standardized tests of global cognition, executive functioning, verbal learning and memory, fine motor functioning, and speed of mental processing administered during comprehensive follow-up evaluations in 2009-2013. We calculated the difference in neuropsychological functioning for a 10% increase in urinary arsenic with adjustment for sex, age, education, and study site.

Results: The sum of inorganic and methylated arsenic species (∑As) in urine was associated with limited fine motor functioning and processing speed. A 10% increase in ∑As was associated with a .10 (95% CI -.20, -.01) decrease on the Finger Tapping Test for the dominant hand and a .13 decrease (95% CI -.21, -.04) for the non-dominant hand. Similarly, a 10% increase in ∑As was associated with a .15 (95% CI -.29, .00) decrease on the Wechsler Adult Intelligence Scale-Fourth Edition Coding Subtest. ∑As was not associated with other neuropsychological functions.

Conclusions: Findings indicate an adverse association between increased urinary arsenic fine motor functioning and processing speed, but not with other neuropsychological functioning, among elderly American Indians.

Keywords: American Indians; Arsenic; Low-level exposure; Neuropsychological functioning; Strong Heart Study.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Aged, 80 and over
  • Arsenic / toxicity*
  • Cognition / drug effects
  • Environmental Exposure*
  • Executive Function / drug effects
  • Female
  • Humans
  • Indians, North American*
  • Male
  • Memory / drug effects
  • Mental Processes / drug effects*
  • Motor Activity / drug effects
  • Neuropsychological Tests
  • United States
  • Verbal Learning / drug effects

Substances

  • Arsenic