Investigation of Whole and Glandular Saliva as a Biomarker for Alzheimer's Disease Diagnosis

Yangyang Cui; Hankun Zhang; Jia Zhu; Zhenhua Liao; Song Wang; Weiqiang Liu

doi:10.3390/brainsci12050595

Investigation of Whole and Glandular Saliva as a Biomarker for Alzheimer's Disease Diagnosis

Brain Sci. 2022 May 3;12(5):595. doi: 10.3390/brainsci12050595.

Authors

Yangyang Cui^{1

2

3}, Hankun Zhang^{1

3}, Jia Zhu^{1

2

3}, Zhenhua Liao³, Song Wang³, Weiqiang Liu^{1

2

3}

Affiliations

¹ Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
² Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.
³ Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China.

Abstract

Salivary Aβ40, Aβ42, t-tau, and p-tau 181 are commonly employed in Alzheimer's disease (AD) investigations. However, the collection method of these biomarkers can affect their levels. To assess the impact of saliva collection methods on biomarkers in this study, 15 healthy people were employed in the morning with six saliva collection methods. The chosen methods were then applied in 30 AD patients and 30 non-AD controls. The levels of salivary biomarkers were calculated by a specific enzyme-linked immunosorbent assay. The receiver operating characteristic was utilized to assess salivary biomarkers in AD patients. The results demonstrated that the highest levels of salivary Aβ40, Aβ42, t-tau, and p-tau were in different saliva collection methods. The correlations between different saliva biomarkers in the same collection method were different. Salivary Aβ40, Aβ42, t-tau, and p-tau had no significant association. Salivary Aβ42 was higher in AD than in non-AD controls. However, p-tau/t-tau and Aβ42/Aβ40 had some relevance. The area under the curve for four biomarkers combined in AD diagnosis was 92.11%. An alternate saliva collection method (e.g., USS in Aβ40, UPS in Aβ42, t-tau, SSS in p-tau 181) was demonstrated in this study. Moreover, combining numerous biomarkers improves AD diagnosis.

Keywords: Alzheimer’s disease; biomarker; collection method; diagnosis; saliva.

Grants and funding

This project was supported by the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2020B1515120082), the Innovation Commission of Science and Technology of Shenzhen Municipality (Grant No. JCYJ20190807144001746, Grant No. JSGG20191129114422849) and the Shenzhen Municipal Industrial and Information Technology Bureau (Grant No. 20180309163834680).