Abstract
BackgroundThe relationship between alterations in thyroid function and cognitive deficits has been investigated in several previous studies. Hypo-or hyperthyroidism and, to a lesser extent, subclinical thyroid dysfunction can negatively affect cognitive performance. However, limited data are available on the potential association of thyroid function with mild cognitive impairment (MCI) and Alzheimer’s disease (AD) in the elderly Chinese population.MethodsIn the present study focusing on a population of elderly Chinese individuals ≥ 50 years of age, 77 cognitively normal controls, 64 patients with MCI, and 154 patients diagnosed with AD underwent assessment of thyroid status using thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and free thyroxine (fT4) levels as variables. Cognitive function was evaluated with the aid of comprehensive neuropsychological tests, such as the Mini-Mental State Examination (MMSE) and Memory and Executive Screening (MES).ResultsOverall, 88.1 % of the subjects displayed normal thyroid function, 4.7 % were diagnosed with clinical hypothyroidism, 3.1 % with subclinical hypothyroidism, and 4.1 % with subclinical hyperthyroidism. After adjusting for covariates (age, sex, education years and body mass index), no association was evident between mild cognitive impairment or AD and thyroid dysfunction. However, lower serum TSH was correlated with risk of AD (odds ratio [OR]: 2.78, 95 % confidence interval [95% CI]: 1.11-6.99).ConclusionNeither hypothyroidism nor subclinical hyperthyroidism was associated with AD and MCI in this population-based elderly Chinese cohort. Our findings need to be confirmed in a longitudinal study.Electronic supplementary materialThe online version of this article (doi:10.1186/s12902-016-0092-z) contains supplementary material, which is available to authorized users.
Highlights
The relationship between alterations in thyroid function and cognitive deficits has been investigated in several previous studies
Screening for thyroid disease is recommended in dementia workup [3], and the serum thyroid stimulating hormone (TSH) level remains a standard screening tool for the routine assessment of patients presenting with cognitive impairment [3]
Individuals selected for cluster sampling in the Jingansi Community, Shanghai, China, from January 2009 to June 2009 were enrolled as the normal control group using the following inclusion criteria: age range from 50 to 90 years, cognitively normal based on the absence of significant impairment in cognitive functions or activities of daily living (ADL), no memory complaints or difficulties, Clinical Dementia Rating (CDR) = 0 [16], Hamilton Depression Rating Score [17] less than or equal to 12 on the 17-item scale in the preceding two weeks, and adequate visual and auditory acuity to allow cognitive testing
Summary
The relationship between alterations in thyroid function and cognitive deficits has been investigated in several previous studies. Limited data are available on the potential association of thyroid function with mild cognitive impairment (MCI) and Alzheimer’s disease (AD) in the elderly Chinese population. Methods: In the present study focusing on a population of elderly Chinese individuals ≥ 50 years of age, 77 cognitively normal controls, 64 patients with MCI, and 154 patients diagnosed with AD underwent assessment of thyroid status using thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and free thyroxine (fT4) levels as variables. Screening for thyroid disease is recommended in dementia workup [3], and the serum thyroid stimulating hormone (TSH) level remains a standard screening tool for the routine assessment of patients presenting with cognitive impairment [3]. Elucidation of thyroid hormone interrelationships in MCI should provide opportunities for earlier intervention in dementia
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