In the past few years, saliva has been proposed to be a promising easily accessible matrix for biomarker quantification (Ng et al., 2024), and several studies show that many AD-related biomarkers [T-tau, P-tau (Shi et al., 2011), Aß peptides (Sabbagh et al., 2018), NfL (Gleerup et al., 2021), glial fibrillary acidic protein (GFAP) (Katsipis et al., 2021), acetylcholine (Ach) (Sayer et al., 2004), and lactoferrin (Gleerup et al., 2021; González-Sánchez et al., 2020; Ashton et al., 2021)] are quantifiable in saliva. Here, MAPT is linked to Alzheimer disease.