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Thyroid Function Abnormalities and Cognitive Impairment in Elderly People: Results of the Invecchiare in Chianti Study |
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| Authors: | Graziano Ceresini MD Fulvio Lauretani MD Marcello Maggio MD Gian Paolo Ceda MD Simonetta Morganti MD Elisa Usberti MD Carlo Chezzi MD Rita Valcavi MD Stefania Bandinelli MD Jack M Guralnik MD Anne R Cappola MD ScM Giorgio Valenti MD Luigi Ferrucci MD PhD |
| Institution: | From the Department of Geriatrics, Endocrine Unit,;Department of Pathology and Laboratory Medicine, University of Parma, Parma, Italy;;ARS Toscana, Firenze, Italy;;Geriatric Unit, Azienda Sanitaria di Toscana, Firenze, Italy;;Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Baltimore, Maryland;;Division of Endocrinology, Diabetes, and Metabolism, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania;and;Longitudinal Studies Section, Clinical Research Branch, National Institute on Aging, Baltimore, Maryland. |
| Abstract: | OBJECTIVES: To investigate thyroid function testing abnormalities in older persons and to explore the relationship between thyroid dysfunction and cognition. DESIGN: Cross-sectional. SETTING: Community-based. PARTICIPANTS: One thousand one hundred seventy-one men and women aged 23 to 102. MEASUREMENTS: Thyroid function was evaluated by measuring plasma concentrations of thyrotropin (TSH), free thyroxine (FT4), and free triiodothyronine (FT3). Cognition was evaluated using the Mini-Mental State Examination (MMSE). Prevalence of overt and subclinical thyroid dysfunction was evaluated in different age groups (<65 vs ≥65). Age trends in TSH, FT4, and FT3 were examined in euthyroid participants. The cross-sectional association between thyroid dysfunction and MMSE score was evaluated adjusting for confounders. RESULTS: Subclinical hypothyroidism and subclinical hyperthyroidism were more prevalent in older than in younger participants (subclinical hypothyroidism, 3.5% vs 0.4%, P <.03; subclinical hyperthyroidism, 7.8% vs 1.9%, P <.002). In euthyroid participants, TSH and FT3 declined with age, whereas FT4 increased. Older participants with subclinical hyperthyroidism had lower MMSE scores than euthyroid subjects (22.61±6.88 vs 24.72±4.52, P <.03). In adjusted analyses, participants with subclinical hyperthyroidism were significantly more likely to have cognitive dysfunction (hazard rate=2.26, P =.003). CONCLUSION: Subtle age-related changes in FT3, FT4, and TSH occur in individuals who remain euthyroid. Subclinical hyperthyroidism is the most prevalent thyroid dysfunction in Italian older persons and is associated with cognitive impairment. |
| Keywords: | thyroid function aging cognition |