Thyroid function abnormalities and cognitive impairment in elderly people: results of the Invecchiare in Chianti study.
OBJECTIVE
To investigate thyroid function testing abnormalities in older persons and to explore the relationship between thyroid dysfunction and cognition.


METHODS
Cross-sectional.


METHODS
Community-based.


METHODS
One thousand one hundred seventy-one men and women aged 23 to 102.


METHODS
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 > or =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).


CONCLUSIONS
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.
Ceresini
Graziano
G
Department of Geriatrics, Endocrine Unit, University of Parma, Italy. ceresini@unipr.it
Lauretani
Fulvio
F
Maggio
Marcello
M
Ceda
Gian Paolo
GP
Morganti
Simonetta
S
Usberti
Elisa
E
Chezzi
Carlo
C
Valcavi
Rita
R
Bandinelli
Stefania
S
Guralnik
Jack M
JM
Cappola
Anne R
AR
Valenti
Giorgio
G
Ferrucci
Luigi
L
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000150:complications*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood* / Q000150:complications; D007037:Hypothyroidism / Q000097:blood* / Q000150:complications; D007558:Italy; D008297:Male; D008875:Middle Aged; D013960:Thyroid Function Tests; D055815:Young Adult