. Author manuscript; available in PMC: 2024 Mar 29.

Published in final edited form as: Nat Aging. 2023 May 18;3(5):506–519. doi: 10.1038/s43587-023-00403-3

Table 1 |.

Current overview of candidate biomarkers with relevance to Alzheimer’s disease

	Fluid biomarkers	Imaging biomarkers
Aβ	Clinical: Aβ₄₂, Aβ₄₂/Aβ₄₀, Aβ₄₂/p-tau Experimental: oligomers of Aβ	Clinical: Aβ PET imaging (for example, ¹¹C[PiB])
AD-like tau	Clinical: p-tau217, p-tau181 Experimental: p-tau231, p-tau212, p-tau205, MTBR-tau and others	Clinical: tau PET imaging (for example, ¹⁸F[flortaucipir])
Neurodegeneration	Clinical: NfL Experimental: neurogranin, NPTX2, SNAP-25, GAP-43, β-synuclein, 14-3-3 and others	Clinical: vMRI, FDG PET Experimental: dMRI, ASL
Astrocytic response	Clinical: GFAP Experimental: YKL-40	Experimental: deprenyl PET and others
Microglial response	Experimental: sTREM2, TAM receptors and others	Experimental: TSPO PET and others

The table divides biomarkers into those that can be measured in fluids (cerebrospinal fluid (CSF) and/or blood) and by brain imaging (positron emission tomography (PET) or magnetic resonance imaging (MRI)). It is important to note that not all fluid biomarkers are relevant to Alzheimer’s disease (AD) when measured in blood but only when measured in CSF (such as neurogranin, soluble triggering receptor expressed on myeloid cells 2 (sTREM2) and YKL-40 (also known as chitinase-3-like protein 1 (CHI3L1)), because they are expressed to a high degree outside the brain as well. The table also indicates biomarkers that might be used in clinical practice and those that are still more experimental. Aβ, amyloid-β; ASL, arterial spin labeling; dMRI, diffusion MRI; FDG PET, fluorodeoxyglucose PET; GAP-43, growth-associated protein, 43 kDa; GFAP, glial fibrillary acidic protein; MTBR, microtubule-binding region; NfL, neurofilament light; NPTX2, neuronal pentraxin 2; PiB, Pittsburgh compound B; SNAP-25, synaptosomal-associated protein, 25 kDa; TSPO, translocator protein, 18 kDa; vMRI, volumetric MRI.