Comparison of Serum Triiodothyronine with Biomarkers for Alzheimer's Disease Continuum in Euthyroid Subjects

• Published in: Journal of Alzheimer's disease Vol. 85; no. 2; p. 605
• Main Authors: Ge, Feifei, Dong, Lin, Zhu, Donglin, Lin, Xingjian, Shi, Jingping, Xiao, Ming
• Format: Journal Article
• Language: English
• Published: Netherlands 01.01.2022
• Subjects: Aged; Alzheimer Disease - metabolism; Alzheimer Disease - physiopathology; Biomarkers - blood; Biomarkers - cerebrospinal fluid; Cognitive Dysfunction - metabolism; Cross-Sectional Studies; Female; Humans; Logistic Models; Male; Middle Aged; Neuropsychological Tests; Prospective Studies; ROC Curve; Thyroid Function Tests; Thyrotropin - blood; Thyrotropin - cerebrospinal fluid; Thyrotropin - metabolism; Triiodothyronine - blood; Triiodothyronine - cerebrospinal fluid; amyloid-β; Alzheimer’s disease; thyroid hormone; biomarkers; cerebrospinal fluid
• ISSN: 1875-8908
• DOI: 10.3233/JAD-215092

Accumulating studies have implicated thyroid dysfunction in the pathogenesis of Alzheimer's disease (AD). This study aimed to explore the association between thyroid hormone (TH) levels and cerebrospinal fluid (CSF) biomarkers for AD continuum among euthyroid subjects. In all, 93 clinically euthyroid subjects with a cognitive decline were included in this prospective cross-sectional study and were divided into groups with abnormal AD biomarkers (belonging to the "Alzheimer's continuum"; A+ patients) and those with "normal AD biomarkers" or "non-AD pathological changes" (A-patients), according to the ATN research framework classification for AD. A partial correlation analysis of serum thyroid-stimulating hormone (TSH) or TH levels with CSF biomarkers was conducted. The predictor for A+ patients was analyzed via binary logistic regressions. Finally, the diagnostic significance of individual biochemical predictors for A+ patients was estimated via receiver operating characteristic curve analysis. Serum total triiodothyronine (TT3) and free triiodothyronine (FT3) levels were found to affect the levels of CSF amyloid-β (Aβ)42 and the ratios of Aβ42/40. Further, FT3 was found to be a significant predictor for A+ via binary logistic regression modeling. Moreover, FT3 showed a high diagnostic value for A+ in euthyroid subjects. Even in a clinical euthyroid state, low serum FT3 and TT3 levels appear to be differentially associated with AD-specific CSF changes. These data indicate that serum FT3 is a strong candidate for differential diagnosis between AD continuum and non-AD dementia, which benefits the early diagnosis and effective management of preclinical and clinical AD patients.