Trace elements in drinking water and the incidence of attention-deficit hyperactivity disorder

Malene Thygesen; Jörg Schullehner; Birgitte Hansen; Torben Sigsgaard; Denitza D Voutchkova; Søren Munch Kristiansen; Carsten B Pedersen; Søren Dalsgaard

doi:10.1016/j.jtemb.2021.126828

Trace elements in drinking water and the incidence of attention-deficit hyperactivity disorder

J Trace Elem Med Biol. 2021 Dec:68:126828. doi: 10.1016/j.jtemb.2021.126828. Epub 2021 Aug 2.

Authors

Malene Thygesen¹, Jörg Schullehner², Birgitte Hansen³, Torben Sigsgaard⁴, Denitza D Voutchkova³, Søren Munch Kristiansen⁵, Carsten B Pedersen⁶, Søren Dalsgaard⁷

Affiliations

¹ National Centre for Register-based Research, Department of Economics and Business, School of Business and Social Sciences, Aarhus University, Aarhus, Denmark; The Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus and Copenhagen, Denmark; Centre for Integrated Register Based Research, CIRRAU, Aarhus University, Aarhus, Denmark. Electronic address: mthygesen@econ.au.dk.
² Department of Public Health, Section of Environment, Occupation and Health, Aarhus University, Aarhus, Denmark; Geological Survey of Denmark and Greenland, GEUS, Denmark; Big Data Centre for Environment and Health, BERTHA, Aarhus University, Aarhus, Denmark.
³ Geological Survey of Denmark and Greenland, GEUS, Denmark.
⁴ Centre for Integrated Register Based Research, CIRRAU, Aarhus University, Aarhus, Denmark; Department of Public Health, Section of Environment, Occupation and Health, Aarhus University, Aarhus, Denmark; Big Data Centre for Environment and Health, BERTHA, Aarhus University, Aarhus, Denmark.
⁵ Department of Geoscience, Aarhus University, Aarhus, Denmark.
⁶ National Centre for Register-based Research, Department of Economics and Business, School of Business and Social Sciences, Aarhus University, Aarhus, Denmark; The Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus and Copenhagen, Denmark; Centre for Integrated Register Based Research, CIRRAU, Aarhus University, Aarhus, Denmark; Big Data Centre for Environment and Health, BERTHA, Aarhus University, Aarhus, Denmark.
⁷ National Centre for Register-based Research, Department of Economics and Business, School of Business and Social Sciences, Aarhus University, Aarhus, Denmark; The Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus and Copenhagen, Denmark; Centre for Integrated Register Based Research, CIRRAU, Aarhus University, Aarhus, Denmark.

PMID: 34391071
DOI: 10.1016/j.jtemb.2021.126828

Abstract

Background: Trace elements have been suggested to have neurotoxic effects and increase the risk of neurodevelopmental disorders, but studies of a potential role of trace elements in relation to Attention-Deficit/Hyperactivity Disorder (ADHD) are very limited. The objective of this study was to conduct an exploratory analysis investigating the associations between 17 geogenic trace elements (Ba, Co, Eu, I, Li, Mo, Rb, Re, Rh, Sb, Sc, Se, Si, Sr, Ti, U and Y) found in Danish drinking water and the risk of developing ADHD.

Methods: In this cohort study, 284,309 individuals, born 1994-2007, were followed for incidence of ADHD from the age of five until the end of study, December 31, 2016. We conducted survival analyses, using Poisson regression to estimate incidence rate ratios (IRRs) with 95 % confidence intervals (CI) in three different confounder adjustment scenarios.

Results: In a model including adjustments for age, sex, calendar year, parental socio-economic status, neighborhood level socio-economic status and parental psychiatric illness, we found that six of the 17 trace elements (Sr, Rb, Rh, Ti, Sb and Re) were associated with an increased risk of ADHD, whereas two (Ba and I) were inversely associated with ADHD. However, when including region as a covariate in the model, most trace elements were no longer associated with ADHD or the association changed direction. Four trace elements (I, Li, Rb, and Y) remained significantly associated with ADHD but in an inverse direction and for three of these (I, Li and Y), we found significant interactions with region in their association with ADHD.

Conclusion: The trace elements under investigation, at levels found in Danish drinking water, do not seem to contribute to the development of ADHD and our findings highlight the importance of examining consistency of associations across geographic areas.

Keywords: ADHD; Drinking water; Neurodevelopment; Trace elements.

MeSH terms

Attention Deficit Disorder with Hyperactivity* / epidemiology
Cohort Studies
Drinking Water*
Humans
Incidence
Trace Elements*

Substances

Drinking Water
Trace Elements