Is thyroid status associated with cognitive impairment in elderly patients in China?

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.

Thyroid function in elderly people: The role of subclinical thyroid disorders in cognitive function and mood alterations

“…Additional data from a cross‐sectional case‐control study showed that long‐term TSH suppressive therapy in elderly patients with differentiated thyroid carcinoma had no clear effects on cognitive function. In another study performed in China, no association was evident between mild cognitive impairment (or Alzheimer's disease) in old patients with subclinical hyperthyroidism . Finally, other cross‐sectional and longitudinal studies reported an association of Alzheimer's disease and dementia in adults with TSH <0.4 mU/L.…”

Altered Serum Marker of Thyroid Profile and Antioxidant Enzymes in Individuals Alzheimer's Disease

“…The thyroid dysfunction appears to be associated with increased oxidative stress and decreased antioxidant enzymes, and enhance neuronal death 11 .The occurrence of thyroid dysfunction has been revealed following the process of dementia progress may result to a decline in exudation of thyroid hormones which leads neurodegeneration 12 . 1.…”

A study of cognitive dysfunctions in patients with thyroid disorders

“…International Journal of Medical Research and Review Available online at: www.ijmrr.in 939 | P a g e also had higher scores of SMMSE than present study. It can be attributed to change in the location and duration of thyroid disorder in the study group [26].…”