Genetically predicted selenium concentrations and thyroid function: A two-sample Mendelian randomization study.

OBJECTIVE: The impact of selenium (Se) on human thyroid function remains unclear, with inconsistent results from recent epidemiological studies. Moreover, the observed associations are prone to bias due to potential confounding and reverse causation. Mendelian randomization (MR) analysis facilitates the large minimization of biases produced by environmental and lifestyle influences, providing unconfounded estimates of causal effects using instrumental variables. We aim to examine the association between Se concentrations and human thyroid function using a two-sample MR analysis. DESIGN AND METHODS: Genetic instruments for Se concentrations, including toenail and blood (TAB) and blood Se concentrations, were identified from a genome-wide association study (GWAS) of blood Se (n = 5477) and toenail Se levels (n = 4162). GWAS summary statistics on thyroid phenotypes were downloaded from the ThyroidOmics consortium, including thyroid-stimulating hormone (TSH) (n = 54,288), free thyroxin (FT4) (n = 49,269), hypo (n = 53,423), and hyperthyroidism (n = 51,823). The MR study was conducted using the inverse-variance weighted (IVW) method, supplemented with the weighted median and the mode-based method. RESULTS: Genetically determined TAB Se was negatively associated with FT4 (ß = -.067; 95% confidence interval [CI] = -0.106, -0.028; p = 0.001) using the IVW analyses, as well in the additional analyses using the weighted median and weighted-mode methods. No evidence in heterogeneity, pleiotropy or outlier single-nucleotide polymorphisms was detected (all p > 0.05). Suggestive casual association between increased genetically determined TAB Se concentrations and decreased hypothyroidism risk was found by the IVW method (odds ratio [OR] = 0.847; 95% CI = 0.728, 0.985; p = 0.031). The causal effect of TAB Se on FT4 was observed in women (ß = -.076; 95% CI = -0.129, -0.024; p = 0.004). However, the influence of genetically determined higher Se concentrations on TSH levels and hyperthyroidism revealed insignificance in the primary and sensitivity analyses. CONCLUSIONS: The present MR study indicated that high Se concentration enable the decreasing of FT4 levels, and the effects of Se concentrations on FT4 remain sex-specific.

Decreased Risk of Dementia Among Patients With Traumatic Brain Injury Receiving Acupuncture Treatment: A Population-Based Retrospective Cohort Study.

OBJECTIVE: We conducted a longitudinal cohort study comparing the effect of acupuncture on the risk of dementia in Taiwanese individuals with traumatic brain injury (TBI). DESIGN AND PARTICIPANTS: A national health insurance database was used to identify 15 440 newly diagnosed TBI patients 20 to 70 years old between 1998 and 2007. Of the identified patients, 6308 received acupuncture following the onset of TBI (acupuncture users) and 9132 patients did not receive acupuncture (nonacupuncture users). MEASURES: All enrollees were followed until the end of 2012 to record incident cases of dementia. A Cox proportional hazards regression model was used to compute adjusted hazard ratios for the relationship of acupuncture use with dementia. RESULTS: During the follow-up period, 249 acupuncture users and 810 nonacupuncture users developed dementia, corresponding to incidence rates of 6.11 and 9.64 per 1000 person-years, respectively. Use of acupuncture was significantly associated with a lower risk of dementia. Those who received more than 5 sessions of acupuncture benefited most from it. CONCLUSIONS: Adding acupuncture to the clinical management of patients with TBI may benefit these patients by decreasing their risk of developing dementia.