Impairment in Working Memory and Executive Function Associated with Mercury Exposure in Indigenous Populations in Upper Amazonian Peru

Alycia K. Silman (), Raveena Chhabria, George W. Hafzalla, Leahanne Giffin, Kimberly Kucharski, Katherine Myers, Carlos Culquichicón, Stephanie Montero, Andres G. Lescano, Claudia M. Vega, Luis E. Fernandez, Miles R. Silman, Michael J. Kane and John W. Sanders
Additional contact information
Alycia K. Silman: Department of Psychology, Wake Forest University, Winston-Salem, NC 27109, USA
Raveena Chhabria: Wake Forest School of Medicine, Winston-Salem, NC 27101, USA
George W. Hafzalla: Wake Forest School of Medicine, Winston-Salem, NC 27101, USA
Leahanne Giffin: Wake Forest School of Medicine, Winston-Salem, NC 27101, USA
Kimberly Kucharski: Wake Forest School of Medicine, Winston-Salem, NC 27101, USA
Katherine Myers: Wake Forest School of Medicine, Winston-Salem, NC 27101, USA
Carlos Culquichicón: Emerge, Emerging Diseases and Climate Change Research Unit, School of Public Health and Administration, Universidad Peruana Cayetano Heredia (UPCH), San Martin de Porres 15102, Peru
Stephanie Montero: Emerge, Emerging Diseases and Climate Change Research Unit, School of Public Health and Administration, Universidad Peruana Cayetano Heredia (UPCH), San Martin de Porres 15102, Peru
Andres G. Lescano: Emerge, Emerging Diseases and Climate Change Research Unit, School of Public Health and Administration, Universidad Peruana Cayetano Heredia (UPCH), San Martin de Porres 15102, Peru
Claudia M. Vega: Centro de Innovación Científica Amazónica, Puerto Maldonado 17001, Peru
Luis E. Fernandez: Center for Energy, Environment, and Sustainability, Wake Forest University, Winston-Salem, NC 27109, USA
Miles R. Silman: Center for Energy, Environment, and Sustainability, Wake Forest University, Winston-Salem, NC 27109, USA
Michael J. Kane: Department of Psychology, University of North Carolina at Greensboro, Greensboro, NC 27412, USA
John W. Sanders: Wake Forest School of Medicine, Winston-Salem, NC 27101, USA

IJERPH, 2022, vol. 19, issue 17, 1-25

Abstract: The Matsigenka people living traditional lifestyles in remote areas of the Amazon rely on a fish-based diet that exposes them to methylmercury (MeHg) at levels that have been associated with decreased IQ scores. In this study, the association between Hg levels and working memory was explored using the framework of the Multicomponent Model. Working memory tasks were modified to fit the culture and language of the Matsigenka when needed and included measures for verbal storage (Word Span) visuospatial storage (Corsi Block Task) and a measure of executive functions, the Self-Ordered Pointing Task (SOPT). An innovation of the Trail Making Tests A & B (TMT A & B) was pilot tested as another potential measure of executive functions. The mean hair Hg levels of 30 participants, ages 12 to 55 years, from three different communities (Maizal, Cacaotal and Yomibato) was 7.0 ppm (sd = 2.40), well above the World Health Organization (WHO) limit for hair of 2.0 ppm and ranged from 1.8 to 14.2 ppm, with 98% of a broader sample of 152 individuals exceeding the WHO limit. Hair Hg levels showed significant associations with cognitive performance, but the degree varied in magnitude according to the type of task. Hg levels were negatively associated with executive functioning performance (SOPT errors), while Hg levels and years of education predicted visuospatial performance (Corsi Block accuracy). Education was the only predictor of Word Span accuracy. The results show that Hg exposure is negatively associated with working memory performance when there is an increased reliance on executive functioning. Based on our findings and the review of the experimental research, we suggest that the SOPT and the Corsi Block have the potential to be alternatives to general intelligence tests when studying remote groups with extensive cultural differences.

Keywords: methylmercury; working memory; executive functions; indigenous population; environmental exposure; Matsigenka; Manu National Park; Amazon Basin (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2022
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