Groundwater Selenium is Associated with Lower Depression Scores: A Project FRONTIER Study

Exposure to environmental factors, such as selenium, can impact psychological functioning.  However, little research has examined the link between groundwater selenium exposure and depression and anxiety among humans.  The current study sought to examine the impact of low levels of groundwater selenium on depression and anxiety among rural-dwelling adults and elders.  Participants included 435 individuals (139 men; 306 women) ages 40 and above (mean age = 62.6, SD= 12.8; mean education = 10.8, SD= 4.4) recruited from an epidemiological study of rural health: Project FRONTIER (Facing Rural Obstacles to healthcare Now Through Intervention, Education & Research).  Utilizing the Environmental Systems Research Institute (ESRI, 2009) ArcGIS (Geographic Information System) software, we created estimates of current selenium exposure through groundwater by combining existing selenium well-water data from the Texas Water Development Board and the Project FRONTIER participants’ residential addresses.  The mean GIS-based selenium estimate was 18.91μg/L.  Using linear regression models, we examined the link between selenium levels and depression (Geriatric Depression Scale) and anxiety (Beck Anxiety Inventory).  The results indicated lower selenium levels were significantly related to higher levels of depression, (B= -0.33, p <0.001).  Additionally, selenium was found to be related to specific depressive symptoms of Dysphoria, Meaninglessness, Apathy, and Cognitive Impairment (p-values <0.05).  However, selenium levels were not significantly associated with anxiety scores or symptoms, with the exception of autonomic symptoms (B= -0.13, p= 0.01).  The significant negative relationship between selenium levels and depression merits further investigation into the possibility of groundwater-based selenium supplementation for the prevention of depression symptoms.