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Open Access Research article

The impact of GPX1 on the association of groundwater selenium and depression: a project FRONTIER study

Leigh A Johnson1*, Jack A Phillips2, Cortney Mauer2, Melissa Edwards3, Valerie Hobson Balldin4, James R Hall5, Robert Barber6, Tori L Conger7, Eric J Ho8 and Sid E O’Bryant9

Author affiliations

1 Department of Internal Medicine, Institute for Aging & Alzheimer’s Disease Research, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA

2 Department of Psychology, Texas Tech University, Lubbock, TX, USA

3 Department of Psychology, University of North Texas, Denton, TX, USA

4 Department of Internal Medicine, University of North Texas Health, Science Center, Fort Worth, TX, USA

5 Department of Psychiatry, University of North Texas Health Science Center, Fort Worth, TX, USA

6 Department of Pharmacology & Neuroscience, Institute for Aging & Alzheimer’s Disease Research, University of North Texas Health Science Center, Fort Worth, TX, USA

7 Department of Internal Medicine, University of North Texas Health Science Center, Fort Worth, TX, USA

8 Texas College of Osteopathic Medicine, University of North Texas Health Science Center, Fort Worth, TX, USA

9 Department of Internal Medicine, Institute for Aging & Alzheimer’s Disease Research, University of North Texas Health Science Center, Fort Worth, TX, USA

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Citation and License

BMC Psychiatry 2013, 13:7  doi:10.1186/1471-244X-13-7

Published: 4 January 2013

Abstract

Background

Prior animal model and human-based studies have linked selenium concentrations to decreased risk for depression; however, this work has not focused on household groundwater levels or specific depressive symptoms. The current study evaluated the link between groundwater selenium levels and depression. We also sought to determine if a functional polymorphism in the glutathione peroxidase 1 (GPX1) gene impacted this link.

Methods

We used a cross-sectional design to analyze data from 585 participants (183 men and 402 women) from Project FRONTIER, a study of rural health in West Texas. Residential selenium concentrations were estimated using Geospatial Information System (GIS) analyses. Linear regression models were created using Geriatric Depression Scale (GDS-30) total and subfactor scores as outcome variables and selenium concentrations as predictor variables. Analyses were re-run after stratification of the sample on GPX1 Pro198Leu genotype (rs1050454).

Results

Selenium levels were significantly and negatively related to all GDS and subfactor scores accounting for up to 17% of the variance beyond covariates. Selenium was most strongly protective against depression among homozygous carriers of the C allele at the Pro198Leu polymorphism of the GPX1 gene. Analyses also point towards a gene-environmental interaction between selenium exposure and GPX1 polymorphism.

Conclusion

Our results support the link between groundwater selenium levels and decreased depression symptoms. These findings also highlight the need to consider the genetics of the glutathione peroxidase system when examining this relationship, as variation in the GPX1 gene is related to depression risk and significantly influences the protective impact of selenium, which is indicative of a gene-environment interaction.

Keywords:
Aging; Depression; Environmental factors; Selenium; GPX1