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

Leigh A Johnson,Melissa Edwards,Jack A Phillips,Cortney Mauer,Valerie Hobson Balldin,Eric J Ho,Tori L Conger,Sid E O’Bryant,James R Hall,Robert Barber

doi:10.1186/1471-244x-13-7

Abstract

BackgroundPrior 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.MethodsWe 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).ResultsSelenium 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.ConclusionOur 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.

Highlights

Prior animal model and human-based studies have linked selenium concentrations to decreased risk for depression; this work has not focused on household groundwater levels or specific depressive symptoms
Past research has shown that low selenium concentrations were related to depression status and other negative affective states [18,20]
Higher groundwater selenium levels were associated with lower scores on the Geriatric Depression Scale

Summary

Introduction

Prior animal model and human-based studies have linked selenium concentrations to decreased risk for depression; this work has not focused on household groundwater levels or specific depressive symptoms. Depression is often associated with lower levels of antioxidants, such as glutathione and GPx, glutathione peroxidase enzyme [16,17]. These findings suggest that selenium may be protective against depression, and selenium supplementation may have the potential to alleviate the symptoms of depression. Gao et al [24] found that higher selenium were associated with lower GDS scores; this effect was no longer significant when cognitive functioning was added to the model This finding is interesting because it suggests that the link between selenium and depression may be impacted by individual factors, such as genetic variants that may impact the selenium levels in the body

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Conclusion