Thyroid function abnormalities and cognitive impairment in elderly people: results of the Invecchiare in Chianti study

Objectives—To investigate thyroid function testing abnormalities in older persons and to explore the relationship between thyroid dysfunction and cognition. Design—Cross-sectional study Setting—Community-based Participants—1171 men and women aged 23-102 yrs Measurements—Thyroid function was evaluated by measuring plasma concentrations of thyrotropin (TSH), free thyroxine (FT4), and free triiodothyronine (FT3). Cognition was evaluated by the Mini Mental State Examination (MMSE). Prevalence of overt and subclinical thyroid dysfunction was evaluated in different age groups (<65 versus ≥65 years). Age trends in TSH, FT4, and FT3 were examined in euthyroid participants. The cross-sectional association of thyroid dysfunction with MMSE score was evaluated adjusting for confounders. Results—Both subclinical hypothyroidism and subclinical hyperthyroidism were more prevalent in older than in younger participants (Subclinical hypothyroidism, 0.4 % vs 3.5 % in younger vs older participants, respectively, P<.03 Subclinical hyperthyroidism, 1.9 % vs 7.8 % in younger v