Table 2.
Detailed presentation of both AD biomarkers and candidate biomarkers and their levels comparison between CSF, blood and saliva.
| Biomarker | CSF | Blood/Plasma | Saliva | |
|---|---|---|---|---|
| AD specific biomarkers (Aβ and TAU) | Aβ isoforms: | |||
| Aβ1-42 | ↓ | Inconsistency | ↑ | |
| Aβ1-40 | Inconsistency | Inconsistency | Unchanged | |
| Aβ1-38 | Inconsistency | Inconsistency | No data | |
| Aβ1-42/Aβ1-40 ratio | ↓ | ↓ | No data | |
| Aβ1-42/Aβ1-38 ratio | ↓ | No data | No data | |
| TAU | ||||
| t-TAU | ↑ | ↑ | ↓ | |
| p-TAU | ↑ | ↑ | ↑ | |
|
AD non-specific biomarkers
Non-Aβ and non-TAU biomarkers |
Inflammation/neuroinflammation biomarkers: | |||
| TREM2 | ↑ | No change | No data | |
| YKL-40 | ↑ | ↑ | No data | |
| IP-10 | Inconsistent | Inconsistent | No data | |
| ICAM1 | ↑ | No data | No data | |
| Synaptic dysfunction biomarkers: | ||||
| Neurogranin * | ↑ | No change | No data | |
| SNAP-25 | ↑ | No data | No data | |
| Synaptotagmin | ↑ | ↓ (limited data) | No data | |
| Secretogranin-2 | ↓ | No data | No data | |
| Neuronal pentraxin 1 | ↓ | No data | No data | |
| Neurofascin | ↓ | No data | No data | |
| Myelin basic protein | ↑ | No data | No data | |
| BACE1 | ↑ | ↑ | No data | |
| α-Synuclein | ↑ | No change | No data | |
| TDP-43 | No data | ↑ | No data | |
| Lactoferrin | No data | No data | ↓ | |
| Acetylcholinesterase | No data | No data | ↓ | |
| Neuronal injury biomarkers: | ||||
| NFL | ↑ | ↑ | No data | |
| VILIP-1 | ↑ | ↑ | No data | |
| Iron toxicity biomarkers: | ||||
| Ferritin | ↑ | No change | No data | |
| hFABP | ↑ | No change | No data |
↓: decreased level in AD compared to controls; ↑: increased level in AD compared to controls; TREM2, triggering receptor expressed on myeloid cells 2; YKL-40, Chitinase-3-like protein 1; IP-10, interferon-γ-induced protein 10; ICAM1, intercellular adhesion molecule 1; *, potentially high degree of AD specificity; SNAP-25, synaptosome-associated protein 25; BACE1, β-site amyloid precursor protein cleaving enzyme 1; TDP-43, transactive response DNA-binding protein 43; NFL, neurofilament light polypeptide; VILIP-1, visinin-like protein 1; hFABP, heart-type fatty acid-binding protein.