The results of this study indicated that MCI participants with depression experienced greater deficits in cognitive functioning than their non-depressed counterparts. Depressed MCI participants exhibited greater deficits in both immediate and delayed memory. Thus, identifying and treating depression in individuals with MCI may improve memory and cognitive functioning.

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.

Background The purpose of the study was to examine the link between GIS-estimated regional specific groundwater levels and neuropsychological functioning in a sample of individuals with and without cognitive impairment. Methods This cross-sectional study design analyzed data from 1390 participants (733 Alzheimer's disease, 127 Mild Cognitive Impairment, and 530 with normal cognition) enrolled in the Texas Alzheimer's Research and Care Consortium. Geographic information systems analyses were used to estimate regional specific groundwater arsenic concentrations using the Environmental Systems Research Institute and arsenic concentrations from the Texas Water Development Board. Results In the full cohort, regional specific arsenic concentrations were positively associated with language abilities (p=0.008), but associated with poorer verbal memory, immediate (p=0.008) and delayed (p<0.001) as well as poorer visual memory, immediate (p=0.02) and delayed (p<0.001). The findings varied by diagnostic category with arsenic being related with cognition most prominently among MCI cases. Conclusions Overall, estimated regional specific groundwater arsenic levels were negatively associated with neuropsychological performance.

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Limited research is available regarding the impact of neuropsychological functioning on health risk behaviors in rural-dwelling elderly populations. This cross-sectional study examined the relationships between estimated premorbid verbal IQ (AMNART), executive functioning impairment (EXIT25), and health risk behaviors including alcohol use (AUDIT), smoking, compliance with recommended cancer screenings, and obesity (BMI). The total sample included 456 English-speaking adults and older adults of non-Hispanic White and Hispanic origin seen as part of an ongoing study of rural cognitive aging, Project FRONTIER. Regression analyses revealed significant independent effects of AMNART and EXIT25 on most health risk behaviors, and supported the hypothesized mediating role of EXIT25 on the relationships between AMNART and smoking, cancer screenings, and BMI in both cognitively impaired and healthy subgroups. This study clarifies the relationships between executive functioning, premorbid IQ, and health risk behaviors in diverse groups, and confirms that premorbid IQ represents an important determinant of health behaviors and neurocognitive outcomes.