Association between Thyroid Hormones, Apolipoprotein E, and Cognitive Function among Cognitively-Normal Elderly Dwellers

Perchlorate, nitrate, and thiocyanate and depression: the potential mediating role of sleep

Perchlorate, nitrate, and thiocyanate are common thyroid disruptors, but it is not clear whether they are related to depression. In this study, we aimed to investigate the association between perchlorate, nitrate, and thiocyanate and depression, and to explore the potential role of sleep in this process. We used data from the National Health and Nutrition Examination Survey (NHANES). From 2005 to 2016, 6 cycles cross-sectional data were combined. Urinary perchlorate, nitrate, and thiocyanate came from laboratory test; depression was diagnosed by the Nine-item Patient Health Questionnaire (PHQ-9). Weighted generalized liner models, restricted cubic splines, and mediation analysis were used in this study. Totally, 16,715 participants were involved in this study, of which 8295 (49.63%) were male and 8420 (50.37%) were female, with an average age of 46.19 ± 0.32 years. We found that urinary thiocyanate concentration was positively associated with depression (Odds ratios [ORs]: 1.49; 95% confidence intervals [95% CIs]: 1.16, 1.91), but not perchlorate (ORs: 0.71; 95% CIs: 0.52, 0.97) or nitrate (ORs: 0.89, 95% CIs: 0.66, 1.19). Sleep may play a potential mediating role between thiocyanate and depression (9.55%). In conclusion, higher concentrations of thiocyanate exposure may be associated with a higher risk of depression, and the sleep duration may be an important mediating factor.

Ageing related thyroid deficiency increases brain-targeted transport of liver-derived ApoE4-laden exosomes leading to cognitive impairment

Alzheimer’s disease (AD) is the prevalent cause of dementia in the ageing world population. Apolipoprotein E4 (ApoE4) allele is the key genetic risk factor for AD, although the mechanisms linking ApoE4 with neurocognitive impairments and aberrant metabolism remains to be fully characterised. We discovered a significant increase in the ApoE4 content of serum exosomes in old healthy subjects and AD patients carrying ApoE4 allele as compared with healthy adults. Elevated exosomal ApoE4 demonstrated significant inverse correlation with serum level of thyroid hormones and cognitive function. We analysed effects of ApoE4-containing peripheral exosomes on neural cells and neurological outputs in aged or thyroidectomised young mice. Ageing-associated hypothyroidism as well as acute thyroidectomy augmented transport of liver-derived ApoE4 reach exosomes into the brain, where ApoE4 activated nucleotide-binding oligomerisation domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome by increasing cholesterol level in neural cells. This, in turn, affected cognition, locomotion and mood. Our study reveals pathological potential of exosomes-mediated relocation of ApoE4 from the periphery to the brain, this process can represent potential therapeutic target.

Association between Hypothyroidism Onset and Alzheimer Disease Onset in Adults with Down Syndrome

Adults with Down syndrome (DS) have an exceptionally high frequency of Alzheimer disease (AD) with a wide variability in onset, from 40 to 70 years of age. Equally prevalent in DS is hypothyroidism. In this study, we sought to quantify the relationship between the two. A total of 232 adults with DS and AD were stratified into three AD onset age groups: early (<47 years), typical (48–59), and late (>59). Among patients with available data, differences in the distributions of demographics, hypothyroidism variables (presence, age of onset), thyroid function tests, thyroid autoantibodies, and APOE genotypes were assessed (e.g., chi-squared, Mann–Whitney tests). Spearman and partial Spearman correlations and ordinal logistic regression models were constructed to quantify the association between ages of AD and hypothyroidism onset with and without covariate adjustments. We observed a positive association between the ages of AD and hypothyroidism onset after accounting for APOE-Ɛ4 (correlation: 0.44, 0.24, 0.60; odds ratio: 1.09, 1.05–1.14). However, an early age of hypothyroidism onset and the presence of the APOE-Ɛ4 allele were independently associated with the early age of AD onset. Similar findings were observed when accounting for other factors. Our study provides evidence for the importance of hypothyroidism and associated pathological mechanisms for risk of AD in DS.