Low vitamin D levels are associated with cognitive impairment in patients with Hashimoto thyroiditis

BackgroundCognitive impairment is commonly observed in patients with Hashimoto thyroiditis (HT). Low levels of vitamin D have been correlated with cognitive impairment in non-HT population. We examined the association of vitamin D levels with cognitive impairment in patients with HT.MethodsWe recruited 194 patients with HT and 200 healthy volunteers. Levels of serum 25-hydroxyvitamin D (25(OH)D) were measured using a competitive protein-binding assay. Cognitive funtion was assessed using Montreal Cognitive Assessment score (MoCA). Subjects with a MoCA scores <26 are considered as having mild cognitive impairment (MCI). Multivariate analysis was performed using logistic regression models.ResultsFifty-five HT patients (28.4%) were diagnosed as having MCI. Patients with MCI had significantly lower 25(OH)D levels when compared with patients without MCI (33.96.2 vs. 44.3 +/- 9.6nmol/L, P<0.001). Significant differences in 25(OH)D quartiles of HT patients were observed between the patients with MCI and the patients without MCI (P<0.001). In multivariate analyses, serum 25(OH)D levels ( 34.0 and47.1nmol/L) were significantly associated with cognitive impairment in patients with HT (OR 6.279, 95% CI 2.673-14.834, P<0.001; OR 0.061, 95% CI 0.008-0.491, P=0.009, respectively).Conclusion Our results demonstrate an important association between serum vitamin D levels and cognitive impairment in patients with HT.