Table 1.

The main biomarkers of Alzheimer’s disease

Biomarker	Change in AD compared with non-AD	Application	References
Aβ42^a	Decreased in CSF and plasma	Used clinically especially in early stage	[52]
Aβ40	Both Aβ40 alone and the ratio of Aβ42/Aβ40 decreased in CSF and plasma	The ratio of Aβ42/Aβ40 used in research	[53]
Aβ38	Both Aβ38 alone and the ratio of Aβ42/Aβ38 decreased in CSF and plasma	The ratio of Aβ42/Aβ38 used in research	[54]
T-tau^a	Increased in CSF and plasma	T-tau used in clinic and the ratio of T-tau/Aβ42 used in research	[55]
P-tau^a	Increased in CSF and plasma	P-tau used in clinic and the ratio of P-tau/Aβ42 used in research	[56]
BACE1	Increased in CSF and plasma	Used widely in research	[57]
hFABP	Increased in CSF	Used widely in research	[58]
TREM2	Increased in CSF TREM2 mRNA increased in blood	Used widely in research	[59]
YKL-40	Increased in CSF	Used widely in research	[60]
SNAP-25	Increased in CSF	Used widely in research	[61]
TDP-43	Increased in CSF and plasma	Used widely in research	[62]
VILIP-1	Increased insignificantly in CSF	Used in disease progression research	[63]
NF-L	Increased in CSF	Used widely in research	[64]
Neurogranin	Increased in CSF	Neurogranin and N/BACE1 ratio used in research	[65, 66]
AD7c-NTP	Increased in urine	Rarely used in research	[49, 50, 67]
24S-OH-Chol	Increased in plasma	Used widely in research	[68]
AAT	Increased in plasma	Used widely in research	[69]
F2-isoprostanes	Increased in CSF	Used in disease progression research	[70]

^aRepresents application in clinic