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Relationship between serum TSH level and Alzheimer disease pathology
Author(s) -
Choi Byung Wook,
Kang Sungmin,
Kim Hae Won
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.041210
Subject(s) - medicine , thyroid stimulating hormone , thyroid , hormone , thyroid function , cognition , endocrinology , cognitive decline , disease , dementia , psychiatry
Background Thyroid dysfunction is one of the risk factors associated with cognitive impairment, including Alzheimer disease (AD). The aim of this study was to evaluate the association between serum TSH level and AD pathology through biochemical assays, positron emission tomography (PET) imaging, and cognitive performance tests. Method Sixty‐nine subjects without overt hypothyroidism who underwent [ 18 F]‐florbetaben PET were included in this prospective cross‐sectional study. The serum levels of free thyroxine (fT4) and thyroid stimulating hormone (TSH) were quantified using radioimmunoassays. The Mini‐Mental State Examination, Digit Span Memory Test, Boston Naming Test, and the Rey‐Osterrieth Complex Figure Test and Recognition Trial were performed to assess cognitive function. Differences in cerebral amyloid‐β (Aβ) burden, which is represented by standardized 18 F‐florbetaben uptake value ratio (SUVR), were compared between high‐normal TSH (TSH ≥ 2.5 μIU/mL) and low‐normal (TSH < 2.5 μIU/mL) groups. Multiple linear regression analyses, adjusted for age and sex, were performed to evaluate the relationship between thyroid hormone levels and cerebral Aβ burden, and between thyroid hormone levels and cognitive function. Result The cerebral Aβ burden in the high‐normal TSH group was significantly higher than in the low‐normal TSH group (SUVR 1.53 vs. 1.35, p = 0.009). The fT4 levels were negatively correlated with cerebral Aβ burden ( β = ‐0.250, p = 0.033), and TSH levels were positively correlated with cerebral Aβ burden ( β = 0.243, p = 0.018). The fT4 level was also positively associated with cognitive function, as inferred from cognitive performance evaluation. Conclusion Serum TSH level is associated with cerebral Aβ burden. The fT4 and TSH levels showed negative and positive correlation with cerebral Aβ burden, respectively. Our findings suggest that serum TSH level, especially in subject with high‐normal serum TSH level, may contribute to AD development.