PT  - JOURNAL ARTICLE
AU  - Chaker, Layal
AU  - Wolters, Frank J.
AU  - Bos, Daniel
AU  - Korevaar, Tim I.M.
AU  - Hofman, Albert
AU  - van der Lugt, Aad
AU  - Koudstaal, Peter J.
AU  - Franco, Oscar H.
AU  - Dehghan, Abbas
AU  - Vernooij, Meike W.
AU  - Peeters, Robin P.
AU  - Ikram, M. Arfan
TI  - Thyroid function and the risk of dementia
AID  - 10.1212/WNL.0000000000003227
DP  - 2016 Oct 18
TA  - Neurology
PG  - 1688--1695
VI  - 87
IP  - 16
4099  - http://n.neurology.org/content/87/16/1688.short
4100  - http://n.neurology.org/content/87/16/1688.full
SO  - Neurology2016 Oct 18; 87
AB  - Objective: To study the role of thyroid function in dementia, cognitive function, and subclinical vascular brain disease with MRI.Methods: Analyses were performed within the Rotterdam Study (baseline 1997), a prospective, population-based cohort. We evaluated the association of thyroid-stimulating hormone (TSH) and free thyroxine with incident dementia using Cox models adjusted for age, sex, cardiovascular risk factors, and education. Absolute risks were calculated accounting for death as a competing risk factor. Associations of thyroid function with cognitive test scores and subclinical vascular brain disease (white matter lesions, lacunes, and microbleeds) were assessed with linear or logistic regression. Additionally, we stratified by sex and restricted analyses to normal thyroid function.Results: We included 9,446 participants with a mean age of 65 years. During follow-up (mean 8.0 years), 601 participants had developed dementia. Higher TSH was associated with lower dementia risk in both the full and normal ranges of thyroid function (hazard ratio [HR] 0.90, 95% confidence interval [CI] 0.83–0.98; and HR 0.76, 95% CI 0.64–0.91, respectively). This association was independent of cardiovascular risk factors. Dementia risk was higher in individuals with higher free thyroxine (HR 1.04, 95% CI 1.01–1.07). Absolute 10-year dementia risk decreased from 15% to 10% with higher TSH in older women. Higher TSH was associated with better global cognitive scores (p = 0.021). Thyroid function was not related to subclinical vascular brain disease as indicated by MRI.Conclusions: High and high-normal thyroid function is associated with increased dementia risk. Thyroid function is not related to vascular brain disease as assessed by MRI, suggesting a role for thyroid hormone in nonvascular pathways leading to dementia.CES-D=Center for Epidemiologic Studies Depression Scale; CI=confidence interval; DSM-III-R=Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Revised; FT4=free thyroxine; HR=hazard ratio; IQR=interquartile range; RS=Rotterdam Study; TPOAb=thyroid peroxidase antibody; TSH=thyroid-stimulating hormone