Selenium Level and Cognitive Function in Rural Elderly Chinese

Department of Medicine, School of Medicine, Indiana University, Indianapolis, IN, USA.
American Journal of Epidemiology (Impact Factor: 5.23). 04/2007; 165(8):955-65. DOI: 10.1093/aje/kwk073
Source: PubMed


Selenium is a trace element associated with antioxidant activity and is considered to be a protective agent against free radicals through enhanced enzyme activity. Studies on selenium and cognitive function or Alzheimer's disease have yielded inconsistent results. A cross-sectional survey of 2,000 rural Chinese aged 65 years or older from two provinces in the People's Republic of China was conducted from December 2003 to May 2005 by use of the Community Screening Instrument for Dementia, the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word List Learning Test, the Indiana University Story Recall Test, the Animal Fluency Test, and the Indiana University Token Test. Over 70% of the study participants have lived in the same village since birth. Nail samples were collected and analyzed for selenium contents. Analysis-of-covariance models were used to estimate the association between quintile selenium levels measured in nail samples and cognitive test scores, with adjustment for other covariates. Lower selenium levels measured in nail samples were significantly associated with lower cognitive scores (p < 0.0087 for all tests) except the Animal Fluency Test (p = 0.4378). A dose-response effect of selenium quintiles was also seen for those significant associations. Results in this geographically stable cohort support the hypothesis that a lifelong low selenium level is associated with lower cognitive function.

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    • "The study was approved by Indiana University Institutional Review Board and the Institute for Environmental Health and Related Safety, Chinese Center for Disease Control and Prevention. Details of the study were described previously [13]. "
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    ABSTRACT: Previous studies have shown that poor cognition and low body mass index were associated with increased mortality. But few studies have investigated the association between cognition and mortality across the entire cognitive spectrum while adjusting for BMI. The objective of this study is to examine the associations between cognitive function, BMI and 7-year mortality in a rural elderly Chinese cohort. A prospective cohort of 2,000 Chinese age 65 and over from four rural counties in China were followed for 7-years. Cognitive function, BMI and other covariate information were obtained at baseline. Cox's proportional hazard models were used to determine the effects of cognitive function and BMI on mortality risk. Of participants enrolled, 473 (23.7%) died during follow-up. Both lower cognitive function (HR = 1.48, p = 0.0049) and lower BMI (HR = 1.6, p < 0.0001) were independently associated with increased mortality risk compared to individuals with average cognitive function and normal weight. Higher cognitive function was associated with lower mortality risk (HR = 0.69, p = 0.0312). We found no significant difference in mortality risk between overweight/obese participants and those with normal weight. Cognitive function and BMI were independent predictors of mortality risk. Intervention strategies for increasing cognitive function and maintaining adequate BMI may be important in reducing morality risk in the elderly population.
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    • "Selenium mediates its effects on brain and behavior development through thyroid hormone metabolism; folate and choline mediate their effects through one-carbon metabolism, DNA methylation, and neurotransmitter synthesis. Life-long selenium deficiency is associated with lower cognitive function (Gao et al., 2007). Folate deficiency can lead to neurological disorders, such as depression and cognitive impairment (Gomez-Pinilla, 2008). "
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    • "Studies that evaluate the relationship between Se levels and cognitive decline suggest that a lack of Se might increase the risk of dementia;17,18 however, the results of various studies are contradictory. Cardoso et al19 and Vural et al20 verified that AD patients had lower Se levels than healthy elderly people, whereas Ceballos-Picot et al21 found an increase in plasma Se levels in AD patients compared to a control group. "
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