Table 2.
Salivary biomarkers for AD.
| Study (Author/Year) |
Biomarker Tested | Biomarker/ Concentration (Saliva) |
Detection Method (Saliva) |
Body Fluids Tested |
|---|---|---|---|---|
| 1. Bermejo- Pareja et al., 2010 [18] |
Aβ42 | Aβ42 markedly elevated in AD patients compared to controls: AD: 6.81 ± 20.04 pg/mL Mild AD: 7.67 ± 16.25 pg/mL Moderate AD: 11.70 ± 34.76 pg/mL Severe AD: 3.03 ± 3.49 pg/mL Control: 2.89 ± 4.96 pg/mL No significant changes with Aβ42 in plasma |
ELISA | Saliva Plasma |
| Aβ40 | Aβ40 unaltered in AD patients compared to controls: AD: 22.3 ± 4.88 pg/mL Mild AD: 21.87 ± 5.7 pg/mL Moderate AD: 21.5 ± 4.17 pg/mL Severe AD: 23.92 ± 4.55 pg/mL Control: 20.82 ± 5.55 pg/mL No significant changes with Aβ40 in plasma |
ELISA | Saliva Plasma |
|
| Aβ42/ Aβ40 ratio |
Aβ42/Aβ40 ratio is moderately (but non-significantly) elevated in patients with mild and moderate AD compared to controls | ELISA | Saliva Plasma |
|
| 2. Shi et al., 2011 [19] |
Aβ42 | Data cannot be extracted Aβ42 not detected in the cohort, neither with Luminex nor with IP/MS |
Luminex IP/MS |
Saliva |
| t-tau | Data cannot be extracted tau detected with IP/MS in saliva t-tau unaltered in patients with AD compared to controls |
Luminex IP/MS |
Saliva | |
| p-tau | Data cannot be extracted p-tau markedly elevated in patients with AD compared to controls |
Luminex | Saliva | |
| p-tau/ t-tau ratio |
Data cannot be extracted p-tau/t-tau ratio significantly elevated in patients with AD compared to controls |
Luminex | Saliva | |
| 3. Kim et al., 2014 [20] | Aβ42 | Data cannot be extracted Aβ42 significantly elevated in patients with severe AD compared to patients with mild AD or controls |
MIA ELISA |
Saliva |
| Aβ40 | Data cannot be extracted Aβ40 non-significantly elevated in patients with severe AD compared to patients with mild AD or controls |
MIA ELISA |
Saliva | |
| Aβ42/Aβ40 ratio | Data cannot be extracted Aβ42/Aβ40 ratio is not elevated in patients with severe or mild AD compared to controls Aβ42/Aβ40 ratio is elevated in patients with severe AD compared to patients with mild AD (significance unclear) |
MIA | Saliva | |
| 4. Lau et al., 2015 [21] |
Aβ42 | Data cannot be extracted Aβ42 not detected in salivary samples of patients with AD or controls |
ELISA | Saliva |
| t-tau | Data cannot be extracted t-tau unaltered in patients with AD compared to controls |
ELISA | Saliva | |
| p-tau | Data cannot be extracted p-tau moderately (but non-significantly) elevated in patients with AD compared to controls |
ELISA | Saliva | |
| p-tau/ t-tau ratio |
Data cannot be extracted p-tau/t-tau ratio moderately (but non-significantly) elevated in patients with AD compared to controls |
ELISA | Saliva | |
| 5. Lee et al., 2017 [22] |
Aβ42 | Aβ42 significantly elevated in AD patients compared to controls Aβ42 markedly elevated in pre-AD patients compared to controls Aβ42 unaltered in AD patients compared to pre-AD patients AD: 59.07 ± 6.33 pg/mL Pre-AD: 56.14 ± 7.12 pg/mL Control: 22.06 ± 0.41 pg/ml |
ELISA | Saliva |
| 6. McGeer et al., 2018 [23] | Aβ42 | Aβ42 significantly elevated in AD patients compared to controls and low controls Aβ42 unaltered in AD patients compared to high controls AD: 53.95 ± 2.24 pg/mL Control: 26.55 ± 1.85 pg/mL High control: 45.96 ± 3.01 pg/mL Low control: 21.54 ± 0.19 pg/mL |
ELISA | Saliva |
| 7. Sabbagh et al., 2018 [24] | Aβ42 | Aβ42 significantly elevated in AD patients compared to controls AD: 51.7 ± 1.6 pg/mL Control: 21.1 ± 0.3 pg/mL |
ELISA | Saliva |
| 8. Pekeles et al., 2019 [25] | p-tau/ t-tau ratio |
Data cannot be extracted p-tau/t-tau ratio significantly elevated in patients with AD compared to controls (for three of the four phosphorylation sites tested) |
Western blot (for saliva) ELISA (for CSF) |
Saliva CSF |
| 9. Ashton et al., 2018 [26] | t-tau | t-tau non-significantly altered among AD, MCI, and controls AD: 12.3 ng/L MCI: 9.8 ng/L Control: 9.6 ng/L |
SIMOA immunoassay | Saliva |
| 10. Tvarijonaviciute et al., 2020 [27] |
Aβ40 | Aβ40 non-significantly elevated in AD patients compared to controls AD: 21.98 ± 16.94 pg/mL Control: 19.97 ± 6.35 pg/mL |
MILLIPLEX® MAP | Saliva |
| Aβ42 | Aβ42 non-significantly decreased in AD patients compared to controls AD: 3.15 ± 0.72 pg/mL Control: 3.57 ± 0.93 pg/mL |
MILLIPLEX® MAP | Saliva | |
| t-tau | t-tau unaltered in patients with AD compared to controls AD: 21.57 ± 22.11 pg/mL Control: 21.15 ± 16.58 pg/mL |
MILLIPLEX® MAP | Saliva | |
| p-tau | p-tau moderately (but non-significantly) decreased in patients with AD compared to controls AD: 40.33 ± 42.95 pg/mL Control: 42.5 ± 38.35 pg/ml |
MILLIPLEX® MAP | Saliva |
CSF: cerebrospinal fluid; ELISA: enzyme-linked immunosorbent assay; IP: immunoprecipitation; MIA: magnetic immunoassay; MS: mass spectrometry; NS: not specified. Biomarker concentrations of main population groups are underlined.