Selenoprotein P concentrations and risk of progression from mild cognitive impairment to dementia

: There is a growing literature investigating the effects of selenium on the central nervous system and cognitive function. However, little is known about the role of selenoprotein P, the main selenium transporter, which can also have adverse biological effects. We conducted a prospective cohort study of individuals aged 42-81 years who received a clinical diagnosis of mild cognitive impairment. Using sandwich ELISA methods, we measured full-length selenoprotein P concentrations in serum and cerebrospinal fluid to assess the relation with dementia incidence during a median follow-up of 47.3 months. We used Cox proportional hazards regression and restricted cubic splines to model such relation. Of the 54 participants, 35 developed dementia during follow-up (including 26 cases of Alzheimer's dementia). Selenoprotein P concentrations in serum and cerebrospinal fluid were highly correlated, and in spline regression analyses they each showed a positive non-linear association with dementia risk, particularly after excluding dementia cases diagnosed within 24 months of follow-up. We also observed differences in association according to the dementia subtypes considered. Risk ratios of dementia peaked at 2-6 at the highest levels of selenoprotein P, when compared to its median level, also depending on matrix, analytical methodology and dementia subtype. Findings of this study, the first to assess selenoprotein P levels in the central nervous system in vivo and the first to use a prospective study design to evaluate associations with dementia, suggest that higher circulating concentrations of selenoprotein P, both in serum and cerebrospinal fluid, predict progression of MCI to dementia. However, further confirmation of these findings is required, given the limited statistical precision of the associations and the potential for residual confounding

Politik und Islam

Wilke B. Politik und Islam. In: Chiari B, Schetter C, eds. Pakistan. Reihe: Wegweiser zur Geschichte; Militärgeschichtliches Forschungsamt. Paderborn: Schöningh; 2010: 155-165

A selenium species in cerebrospinal fluid predicts conversion to Alzheimer's dementia in persons with mild cognitive impairment

Little is known about factors influencing progression from mild cognitive impairment to Alzheimer's dementia. A potential role of environmental chemicals and specifically of selenium, a trace element of nutritional and toxicological relevance, has been suggested. Epidemiologic studies of selenium are lacking, however, with the exception of a recent randomized trial based on an organic selenium form

Association between selenium species and hippocampal volume in subjects with mild cognitive impairment

Background Selenium is a trace element with nutritional and toxicological properties. Its influence on human health is thought to depend on exposure dose and chemical form. The effects of selenium exposure on medical conditions that involve the central nervous system have been insufficiently studied. In a cohort of individuals with mild cognitive impairment, we have previously documented a positive relation between cerebrospinal fluid (CSF) levels of inorganic hexavalent selenium (selenate) and risk of dementia. Methods/Approach We assessed the relation between CSF levels of selenium species and volume of the hippocampus among the 33 cohort members aged 43-82 years who had undergone magnetic resonance imaging at baseline (2008-2014) using both linear and spline regression analyses. We also performed a surface-based analysis using SPHARM-PDM to evaluate differences in shape of the hippocampus in addition to its volume in relation to CSF levels of selenium species. Results We found an inverse association between selenate and total hippocampal volume (β regression coefficient in multivariable linear regression analysis -3.05, 95% confidence interval -5.74 to -0.37), which was similar for the right and left hippocampus and emerged mainly at the highest exposure levels. We found little association between the other selenium forms and hippocampal volume. In the surface-based analysis, the left hippocampus showed considerably more pronounced shape differences in the ventro-medial region of the head. Conclusions This is the first study to analyze selenium species in relation to hippocampal volume and structure, suggesting that a selenium form with high toxicological potential may adversely affect a key structure involved in dementia onset and progression as the hippocampus, possibly the left one in particular. However, we cannot entirely rule out the influence of reverse causation or unmeasured confounding on these results