Prevalence of thyroid dysfunction and its impact on cognition in older mexican adults: (SADEM study).
BACKGROUND
Subclinical thyroid dysfunction is a possible risk factor for cognitive impairment in old age, but results are inconsistent. Aim of the present study was to evaluate the prevalence of thyroid dysfunction among older community-dwelling adults and to see whether thyroid function impacts the cognitive status of the elderly.


METHODS
We included 1750 participants from the Study on Aging and Dementia in Mexico (SADEM). All subjects were evaluated clinically via specific interviews. TSH levels were analyzed by chemiluminescent immunometry assay. We classified participants into five thyroid state groups: (1) normal TSH levels (0.40-4.0 IU/L) were considered euthyroid; (2) Overt hyperthyroidism: TSH <0.3 IU/l and FT4 >23 pmol/l; (3) Overt hypothyroidism: TSH >4.8 IU/l, FT4 <13 pmol/l; (4) Subclinical hyperthyroidism: TSH <0.3 IU/l, FT4: 13-23 pmol/l; (5) Subclinical hypothyroidism: TSH >4.8 IU/l, FT4: 13-23 pmol/l.


RESULTS
The overall estimated prevalence of thyroid dysfunction in Mexican population was 23.7% (95% CI, 22.66-26.77). Of these, 15.4% older adults were classified as subclinical hypothyroidism, 7.2% overt hypothyroidism, 0.5% subclinical hyperthyroidism, and 0.6% overt hyperthyroidism. The association of thyroid dysfunction with cognitive impairment was most evident in overt hypothyroidism OR = 1.261 (1.185-1.343).


CONCLUSIONS
The present study demonstrated a high prevalence of thyroid dysfunction in Mexican elderly people living in the community. A relationship between cognitive impairment and the presence of hypothyroidism was also shown, and to a lesser degree in hyperthyroidism.
Unidad de Investigación en Epidemiología Clínica, Hospital General Regional No 1 Carlos McGregor Sánchez Navarro, Gabriel Mancera 222, Colonia Del Valle, Delegación, Benito Juárez, 03100, México, DF, Mexico. teresa.juarez@imss.gob.mx.|High Studies (FES) Zaragoza, National Autonomous University of Mexico, Mexico City, Mexico. teresa.juarez@imss.gob.mx.
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Juárez-Cedillo
Endocrine Research Unit, National Medical Center, Mexican Institute of Social Security, Mexico City, Mexico.
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Basurto-Acevedo
Endocrine Research Unit, National Medical Center, Mexican Institute of Social Security, Mexico City, Mexico.
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Vega-García
Gerontology Research Unit. Faculty of High Studies (FES) Zaragoza, National Autonomous University of Mexico, Mexico City, Mexico.
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Sánchez-Rodríguez Martha
Gerontology Research Unit. Faculty of High Studies (FES) Zaragoza, National Autonomous University of Mexico, Mexico City, Mexico.
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Retana-Ugalde
Unidad de Investigación en Epidemiología Clínica, Hospital General Regional No 1 Carlos McGregor Sánchez Navarro, Gabriel Mancera 222, Colonia Del Valle, Delegación, Benito Juárez, 03100, México, DF, Mexico.
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Juárez-Cedillo
High Studies (FES) Zaragoza, National Autonomous University of Mexico, Mexico City, Mexico.
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Gonzalez-Melendez Roberto
Unidad de Investigación en Epidemiología Clínica, Hospital General Regional No 1 Carlos McGregor Sánchez Navarro, Gabriel Mancera 222, Colonia Del Valle, Delegación, Benito Juárez, 03100, México, DF, Mexico.
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Escobedo-de-la-Peña
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood / Q000523:psychology*; D010054:Brief Psychiatric Rating Scale; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000097:blood / Q000453:epidemiology / Q000523:psychology; D003704:Dementia / Q000097:blood / Q000453:epidemiology* / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D013959:Thyroid Diseases / Q000097:blood / Q000453:epidemiology* / Q000523:psychology*; D013961:Thyroid Gland / Q000378:metabolism
Cognitive function; Elderly; Mexico; SADEM; Thyroid function